Supported HL focus. First assessment 2021; current through 2028. First-assessment-2029 course is separate.. Remaining guide, assessment and practical requirements retain their recorded holds.
Prerequisites: read the stated quantities and units, use arithmetic and the model conditions below. Each lesson develops its own method before independent transfer.
These are original or explicitly fictional teaching examples, not actual measurements or completed assessed learner investigations.
1.2
Exact arithmetic and estimation
English
Can we pack without leftovers?
A supplier packs 72 pencils and 90 pens into identical gift bags. How can we avoid leftovers?
This lesson studies prime factor 质因数: A prime number that divides the integer exactly.
Choose the mathematical structure
Prime factors reveal shared structure. Use the smallest common prime powers for the HCF and the largest for the LCM. Estimate before calculating; use brackets to preserve the order of operations.
State the allowed inputs and units before calculating. An equation should express the relationship, not just record a calculator entry.
Check the result against the starting quantities. Substitute into the original relation, or compare the graph and numerical answer where appropriate.
Example:
72=2^3×3^2 and 90=2×3^2×5. Their HCF is 2×9=18. Make 18 bags with 4 pencils and 5 pens each. Their LCM is 2^3×3^2×5=360.
Test a tempting shortcut
The HCF divides both numbers; the LCM is a multiple of both. They answer different questions. A decimal estimate is not an exact fraction.
When a shortcut fails, identify the assumption it breaks. Keep an exact value until the requested final rounding.
Warn:
The HCF of two positive integers is always larger than either integer. This claim is false. Explain which definition or assumption it violates.
Interpret a new situation
For a non-calculator paper, keep fractions exact and show cancellation. For a calculator paper, enter the full expression and compare with your estimate.
A complete solution gives the mathematical result and explains what it means. Check that it is possible in the stated context.
Use this in your course
Current first-assessment-2021 Applications and Interpretation HL. This is authored concept support; the full guide is needed to certify every objective.
Give the method before the final answer, and use the paper's calculator and formula rules. Review a wrong answer by locating the first invalid step.
Key:
A prime number that divides the integer exactly. Choose the relationship, show the method, check its assumptions and interpret the result.
A coat is reduced by 20% to ¥240. The discount applies to the original price, not to the sale price.
This lesson studies multiplier 乘数: A factor that performs a percentage change in one multiplication.
Choose the mathematical structure
A p% increase has multiplier 1+p/100; a decrease has multiplier 1-p/100. Reverse a percentage by dividing by the multiplier. In a ratio, first find the total number of parts.
State the allowed inputs and units before calculating. An equation should express the relationship, not just record a calculator entry.
Check the result against the starting quantities. Substitute into the original relation, or compare the graph and numerical answer where appropriate.
Example:
Let the original price be P. The model is sale price=0.8P. Hence P=240/0.8=300. A later 20% increase gives 240×1.2=288, so the two changes do not cancel.
Test a tempting shortcut
A percentage uses a stated base. Subtracting the percentages loses that base. For compound change, multiply the multipliers; do not add the percentages.
When a shortcut fails, identify the assumption it breaks. Keep an exact value until the requested final rounding.
Warn:
A 20% decrease followed by a 20% increase restores the starting price. This claim is false. Explain which definition or assumption it violates.
Interpret a new situation
For direct proportion use y=kx; for inverse proportion use y=k/x. Calculate k from a known pair before using a new value. State what you held constant.
A complete solution gives the mathematical result and explains what it means. Check that it is possible in the stated context.
Use this in your course
Current first-assessment-2021 Applications and Interpretation HL. This is authored concept support; the full guide is needed to certify every objective.
Give the method before the final answer, and use the paper's calculator and formula rules. Review a wrong answer by locating the first invalid step.
Key:
A factor that performs a percentage change in one multiplication. Choose the relationship, show the method, check its assumptions and interpret the result.
A saving plan adds ¥30 more each week; a population model grows by 5% each year. Equal differences and equal ratios need different models.
This lesson studies common ratio 公比: The constant multiplier between consecutive terms of a geometric sequence.
Choose the mathematical structure
For an arithmetic progression, u_n=a+(n-1)d and S_n=n(2a+(n-1)d)/2. For a geometric progression, u_n=ar^(n-1) and S_n=a(1-r^n)/(1-r). An infinite geometric sum exists only if |r|<1.
State the allowed inputs and units before calculating. An equation should express the relationship, not just record a calculator entry.
Check the result against the starting quantities. Substitute into the original relation, or compare the graph and numerical answer where appropriate.
Example:
For a=5,d=3,n=8, u_8=5+7×3=26 and S_8=8(10+21)/2=124. For a=12,r=1/2, S infinity=12/(1-1/2)=24. For u_(n+1)=2u_n+1 with u_1=1, the next terms are 3,7,15.
Test a tempting shortcut
The first term has index 1, so the exponent is n-1. A sequence is a list; a series is a sum. A geometric sequence can alternate in sign and still converge.
When a shortcut fails, identify the assumption it breaks. Keep an exact value until the requested final rounding.
Warn:
Every geometric series has a finite sum to infinity. This claim is false. Explain which definition or assumption it violates.
Interpret a new situation
Explain whether the context justifies additive or multiplicative change. In finance, distinguish a single deposit from a stream of deposits before choosing a sum formula.
A complete solution gives the mathematical result and explains what it means. Check that it is possible in the stated context.
Use this in your course
Current first-assessment-2021 Applications and Interpretation HL. This is authored concept support; the full guide is needed to certify every objective.
Give the method before the final answer, and use the paper's calculator and formula rules. Review a wrong answer by locating the first invalid step.
Key:
The constant multiplier between consecutive terms of a geometric sequence. Choose the relationship, show the method, check its assumptions and interpret the result.
A line predicts bus travel time from distance. A small calculation error matters less than using a model outside its evidence.
This lesson studies residual 残差: The observed value minus the value predicted by a fitted model.
Choose the mathematical structure
A linear model y=a+bx has intercept a and slope b with contextual units. Inspect residuals and the data range. For repeated percentage change use a geometric model; for a loan distinguish principal, rate, repayment and period.
State the allowed inputs and units before calculating. An equation should express the relationship, not just record a calculator entry.
Work through a checked case
$$\widehat t=8+2d,\qquad e=t-\widehat t$$
Check the result against the starting quantities. Substitute into the original relation, or compare the graph and numerical answer where appropriate.
Example:
The fitted model t=8+2d predicts 18 minutes at d=5 km. If the observed time is 21, the residual is 3 minutes. A ¥1000 deposit at 5% compound annual interest becomes 1000×1.05³=1157.625 after 3 years.
Test a tempting shortcut
A good fit does not prove a causal mechanism. A correlation coefficient measures linear association, not the gradient. Calculator output must be translated into a model, checked and interpreted.
When a shortcut fails, identify the assumption it breaks. Keep an exact value until the requested final rounding.
Warn:
A high correlation permits reliable extrapolation to any distance. This claim is false. Explain which definition or assumption it violates.
Interpret a new situation
In IB AI, record the data source, domain, assumptions and calculator method. Compare an alternative model and judge predictions against residuals. A financial answer must state payment timing and whether interest is compounded.
A complete solution gives the mathematical result and explains what it means. Check that it is possible in the stated context.
Use this in your course
Current first-assessment-2021 Applications and Interpretation HL. This is authored concept support; the full guide is needed to certify every objective.
Give the method before the final answer, and use the paper's calculator and formula rules. Review a wrong answer by locating the first invalid step.
Key:
The observed value minus the value predicted by a fitted model. Choose the relationship, show the method, check its assumptions and interpret the result.
A map stretches one direction and shears another. A matrix records the transformation of each basis vector.
This lesson studies determinant 行列式: A scalar that determines whether a square matrix is invertible and, in two dimensions, its signed area factor.
Choose the mathematical structure
A 2×2 matrix [[a,b],[c,d]] has determinant ad-bc and inverse [[d,-b],[-c,a]]/(ad-bc) if the determinant is nonzero. Transform column vectors by left multiplication. The rightmost matrix acts first in a product.
State the allowed inputs and units before calculating. An equation should express the relationship, not just record a calculator entry.
Check the result against the starting quantities. Substitute into the original relation, or compare the graph and numerical answer where appropriate.
Example:
For A=[[2,1],[0,3]], det A=6. A(1,2)=(4,6). Its inverse is [[1/2,-1/6],[0,1/3]]. The characteristic equation is (2-λ)(3-λ)=0, so the eigenvalues are 2 and 3.
Test a tempting shortcut
Matrix multiplication is usually not commutative. A determinant of zero means the transformation loses a dimension and has no inverse. Eigenvalues and diagonalisation are advanced scope, not ordinary GCSE vector content.
When a shortcut fails, identify the assumption it breaks. Keep an exact value until the requested final rounding.
Warn:
Every square matrix has an inverse. This claim is false. Explain which definition or assumption it violates.
Interpret a new situation
Find an eigenvector by solving (A-λI)v=0 with v≠0. Explain the geometrical meaning: this vector keeps its line direction under the transformation.
A complete solution gives the mathematical result and explains what it means. Check that it is possible in the stated context.
Use this in your course
Current first-assessment-2021 Applications and Interpretation HL. This is authored concept support; the full guide is needed to certify every objective.
Give the method before the final answer, and use the paper's calculator and formula rules. Review a wrong answer by locating the first invalid step.
Key:
A scalar that determines whether a square matrix is invertible and, in two dimensions, its signed area factor. Choose the relationship, show the method, check its assumptions and interpret the result.
The equation x²+1=0 has no real roots. Extending the number system lets us represent and calculate with both roots.
This lesson studies complex conjugate 共轭复数: The number obtained by reversing the sign of the imaginary part.
Choose the mathematical structure
Write z=a+bi with i²=-1. The conjugate is a-bi and z times its conjugate=a²+b². The modulus is √(a²+b²); the argument needs the correct quadrant. Conjugate roots occur for polynomials with real coefficients.
State the allowed inputs and units before calculating. An equation should express the relationship, not just record a calculator entry.
Check the result against the starting quantities. Substitute into the original relation, or compare the graph and numerical answer where appropriate.
Example:
For z=3+4i, |z|=5 and z conjugate=3-4i. The reciprocal is (3-4i)/25. For x²-6x+13=0, the roots are 3±2i. Multiplying by the conjugate makes a complex denominator real.
Test a tempting shortcut
The square root of a sum is not the sum of the square roots. An inverse tangent alone may return the wrong quadrant. Do not confuse modulus with squared modulus.
When a shortcut fails, identify the assumption it breaks. Keep an exact value until the requested final rounding.
Warn:
For a+bi, its modulus is always a+b. This claim is false. Explain which definition or assumption it violates.
Interpret a new situation
Draw the real axis horizontally and imaginary axis vertically. For products, moduli multiply and arguments add; powers extend this geometric pattern through de Moivre's theorem.
A complete solution gives the mathematical result and explains what it means. Check that it is possible in the stated context.
Use this in your course
Current first-assessment-2021 Applications and Interpretation HL. This is authored concept support; the full guide is needed to certify every objective.
Give the method before the final answer, and use the paper's calculator and formula rules. Review a wrong answer by locating the first invalid step.
Key:
The number obtained by reversing the sign of the imaginary part. Choose the relationship, show the method, check its assumptions and interpret the result.
ระบุ domain และ range สำหรับฟังก์ชันกลับกัน ต้องตรวจสอบก่อนว่าฟังก์ชันนั้นเป็น one-to-one บนโดเมน Composition fg หมายถึงนำ g ไปใช้ก่อน แล้วจึงนำ f ไปใช้ ผลลัพธ์กลางต้องเป็นค่าอินพุกที่ f อนุญาตให้ใช้
Supported HL focus. First assessment 2021; current through 2028. First-assessment-2029 course is separate.. Remaining guide, assessment and practical requirements retain their recorded holds.
Prerequisites: read the stated quantities and units, use arithmetic and the model conditions below. Each lesson develops its own method before independent transfer.
These are original or explicitly fictional teaching examples, not actual measurements or completed assessed learner investigations.
5.2
อนุพันธ์และจุดคงที่
English
What is the slope at one point?
A curved road has different slopes at different positions. An average gradient cannot describe every point.
This lesson studies derivative 导数: The instantaneous rate of change, also the gradient of a tangent.
Choose the mathematical structure
For y=ax^n, dy/dx=anx^(n-1). A stationary point satisfies dy/dx=0. Check the sign change of the derivative, or the second derivative when it is nonzero, to classify it.
State the allowed inputs and units before calculating. An equation should express the relationship, not just record a calculator entry.
Check the result against the starting quantities. Substitute into the original relation, or compare the graph and numerical answer where appropriate.
Example:
For y=x³-3x, dy/dx=3x²-3. At x=1, the gradient is 0 and y=-2. The second derivative is 6x, positive at x=1, so this is a local minimum. At x=-1, y=2 and the second derivative is negative, giving a local maximum.
Test a tempting shortcut
A zero derivative does not always mean a maximum or minimum: y=x³ is stationary at 0 but continues increasing. An endpoint can also produce an extreme value on a restricted domain.
When a shortcut fails, identify the assumption it breaks. Keep an exact value until the requested final rounding.
Warn:
Every point with zero derivative is a local maximum or minimum. This claim is false. Explain which definition or assumption it violates.
Interpret a new situation
At GCSE/IGCSE use only the polynomial scope allowed by the tier; do not add chain, product or quotient rules there. At advanced level, connect the derivative to rates and optimization with a valid domain.
A complete solution gives the mathematical result and explains what it means. Check that it is possible in the stated context.
Use this in your course
Current first-assessment-2021 Applications and Interpretation HL. This is authored concept support; the full guide is needed to certify every objective.
Give the method before the final answer, and use the paper's calculator and formula rules. Review a wrong answer by locating the first invalid step.
Key:
The instantaneous rate of change, also the gradient of a tangent. Choose the relationship, show the method, check its assumptions and interpret the result.
A nonlinear equation has no convenient exact solution. An approximation still needs evidence that it is reliable.
This lesson studies iteration 迭代: A repeated update in which each new approximation is calculated from the previous one.
Choose the mathematical structure
A continuous function with opposite signs at two endpoints has a root between them. Newton's method uses x next=x-f(x)/f prime(x), with a nonzero derivative. The trapezium rule approximates a definite integral using endpoint heights.
State the allowed inputs and units before calculating. An equation should express the relationship, not just record a calculator entry.
Work through a checked case
$$x_{n+1}=x_n-\frac{f(x_n)}{f^{\prime}(x_n)}$$
Check the result against the starting quantities. Substitute into the original relation, or compare the graph and numerical answer where appropriate.
Example:
For f(x)=x²-2 and x₀=1.5, Newton gives x₁=1.5-(2.25-2)/3=1.4166667. With y=x² on [0,2] and two equal strips, h=1 and trapezium area=(1/2)(0+2×1+4)=3; the exact area is 8/3.
Test a tempting shortcut
A sign change across a discontinuity does not prove a root. Iteration can diverge or cycle. The trapezium rule's overestimate or underestimate depends on curvature, not just whether the function increases.
When a shortcut fails, identify the assumption it breaks. Keep an exact value until the requested final rounding.
Warn:
Every sign change proves a root, including one across a discontinuity. This claim is false. Explain which definition or assumption it violates.
Interpret a new situation
Give a stopping criterion and report sensible accuracy. Confirm the approximated root by a sign bracket around the stated rounded answer; explain any failure of the chosen iteration.
A complete solution gives the mathematical result and explains what it means. Check that it is possible in the stated context.
Use this in your course
Current first-assessment-2021 Applications and Interpretation HL. This is authored concept support; the full guide is needed to certify every objective.
Give the method before the final answer, and use the paper's calculator and formula rules. Review a wrong answer by locating the first invalid step.
Key:
A repeated update in which each new approximation is calculated from the previous one. Choose the relationship, show the method, check its assumptions and interpret the result.
Check the result against the starting quantities. Substitute into the original relation, or compare the graph and numerical answer where appropriate.
Example:
For y=(3x+1)^4, y prime=4(3x+1)^3×3=12(3x+1)^3. At x=0, the gradient is 12. For x²+y²=25, differentiate implicitly: 2x+2y y prime=0, so y prime=-x/y when y≠0.
Test a tempting shortcut
A derivative of a product is not the product of the derivatives. In implicit differentiation, every differentiated function of y brings a dy/dx factor. A quotient's denominator is squared.
When a shortcut fails, identify the assumption it breaks. Keep an exact value until the requested final rounding.
Warn:
The derivative of u(x)v(x) is always u prime times v prime. This claim is false. Explain which definition or assumption it violates.
Interpret a new situation
Choose a useful form before differentiating: expanding a short polynomial may be simpler. For related rates, write the relation in symbols, differentiate with respect to time, then substitute measured values.
A complete solution gives the mathematical result and explains what it means. Check that it is possible in the stated context.
Use this in your course
Current first-assessment-2021 Applications and Interpretation HL. This is authored concept support; the full guide is needed to certify every objective.
Give the method before the final answer, and use the paper's calculator and formula rules. Review a wrong answer by locating the first invalid step.
Key:
The rule that multiplies the outer derivative by the inner derivative for a composite function. Choose the relationship, show the method, check its assumptions and interpret the result.
A simple-looking product such as xe^x cannot be integrated by separately integrating each factor.
This lesson studies integration by parts 分部积分法: An integration method based on the derivative of a product.
Choose the mathematical structure
Use substitution when an inner derivative appears as a factor. By parts, integral u v prime =uv-integral u prime v. For a rational function, divide first if needed, then decompose into partial fractions.
State the allowed inputs and units before calculating. An equation should express the relationship, not just record a calculator entry.
Work through a checked case
$$\int u v^{\prime}\,dx=uv-\int u^{\prime}v\,dx$$
Check the result against the starting quantities. Substitute into the original relation, or compare the graph and numerical answer where appropriate.
Example:
For integral xe^x dx, take u=x and v prime=e^x. Then the integral is xe^x-e^x+C. For integral 2x/(x²+1) dx, substitute w=x²+1, dw=2x dx; the answer is ln(x²+1)+C.
Test a tempting shortcut
Choosing u and v prime well matters: the remaining integral should become simpler. In a definite substitution, either change the limits or return to x before applying the original limits.
When a shortcut fails, identify the assumption it breaks. Keep an exact value until the requested final rounding.
Warn:
The integral of a product equals the product of its separate integrals. This claim is false. Explain which definition or assumption it violates.
Interpret a new situation
Check by differentiating. For volumes of revolution around the x-axis use V=π integral y² dx; do not confuse the square of a function with the integral of the function.
A complete solution gives the mathematical result and explains what it means. Check that it is possible in the stated context.
Use this in your course
Current first-assessment-2021 Applications and Interpretation HL. This is authored concept support; the full guide is needed to certify every objective.
Give the method before the final answer, and use the paper's calculator and formula rules. Review a wrong answer by locating the first invalid step.
Key:
An integration method based on the derivative of a product. Choose the relationship, show the method, check its assumptions and interpret the result.
A growing population's rate is proportional to its current size. The rate equation describes a whole family until an initial population is supplied.
This lesson studies initial condition 初始条件: A specified value that selects a particular solution from a family.
Choose the mathematical structure
For dy/dx=ky, separate variables: dy/y=k dx, giving y=Ae^(kx). Use an initial condition to find A. Euler's method takes y next=y+h f(x,y), with a chosen step h.
State the allowed inputs and units before calculating. An equation should express the relationship, not just record a calculator entry.
Work through a checked case
$$\frac{dy}{dx}=ky,\qquad y=Ae^{kx}$$
Check the result against the starting quantities. Substitute into the original relation, or compare the graph and numerical answer where appropriate.
Example:
With dy/dx=0.5y and y(0)=2, y=2e^(0.5x). Euler with h=0.2 gives y(0.2)≈2+0.2×1=2.2 and y(0.4)≈2.2+0.2×1.1=2.42. The exact second value is about 2.4428.
Test a tempting shortcut
An initial condition determines the integration constant; it is not a replacement for integrating. Dividing by y can omit an equilibrium solution y=0. Euler accuracy depends on step size and the equation.
When a shortcut fails, identify the assumption it breaks. Keep an exact value until the requested final rounding.
Warn:
Every step size gives exactly the same Euler approximation. This claim is false. Explain which definition or assumption it violates.
Interpret a new situation
For second-order linear equations, combine the complementary function with an appropriate particular integral, then apply the required initial conditions. This is Further Pure scope; check the named unit.
A complete solution gives the mathematical result and explains what it means. Check that it is possible in the stated context.
Use this in your course
Current first-assessment-2021 Applications and Interpretation HL. This is authored concept support; the full guide is needed to certify every objective.
Give the method before the final answer, and use the paper's calculator and formula rules. Review a wrong answer by locating the first invalid step.
Key:
A specified value that selects a particular solution from a family. Choose the relationship, show the method, check its assumptions and interpret the result.
การสำรวจทางคณิตศาสตร์ภายใต้การดูแลของโรงเรียนสามารถถูกแทนที่ด้วยการทดสอบ模擬 (mock exam) แบบเขียน限时 This claim is false. อธิบายว่ามันละเมิดนิยามหรือสมมติฐานใด