A-Level · Mathematics · AQA · Mark scheme decoded
AQA A-Level Mathematics: Integration of Basic Functions and Trigonometric Functions — mark scheme explained
The short answer
In AQA A-Level Mathematics, integration is a fundamental concept that allows us to find the antiderivative (or indefinite integral) of various functions. This spec point focuses on integrating x n (excluding n = -1 ), and related sums, differences, and constant multiples.
The question
Find the indefinite integral of 2x 4 - 3x 2 + 1 . [Paraphrased for study — not reproduced from any exam paper.]
Mark scheme, decoded
What each mark is really for — in plain English — and the wording trap that loses it.
- S1
Step 1: Integrate each term separately.
- S2
∫ (2x 4 ) dx = (2/5) x 5
- S3
∫ (-3x 2 ) dx = -x 3
- S4
∫ 1 dx = x
- S5
Step 2: Combine the results and add the constant of integration.
- S6
(2/5) x 5 - x 3 + x + C
Model answer
Worked through, with each step tagged to the mark it earns.
- S1
Step 1: Integrate each term separately.
- S2
∫ (2x 4 ) dx = (2/5) x 5
- S3
∫ (-3x 2 ) dx = -x 3
- S4
∫ 1 dx = x
- S5
Step 2: Combine the results and add the constant of integration.
- S6
(2/5) x 5 - x 3 + x + C
Final answer: (2/5) x 5 - x 3 + x + C
Common mistakes
- Forgetting to add the constant of integration C . — Always include + C at the end of your answer when finding an indefinite integral.
- Incorrectly applying the power rule to x -1 . — Memorize that ∫ (1/x) dx = ln|x| + C and use this formula instead of the power rule.
- Forgetting to divide by the coefficient of x when integrating exponential functions. — Always divide by the coefficient of x when integrating exponential functions with a linear argument.
- Incorrectly applying the integral of trigonometric functions. — Memorize that ∫ sin(kx) dx = -(1/k) cos(kx) + C and ∫ cos(kx) dx = (1/k) sin(kx) + C . Always check the sign and the coefficient in the denominator.
- Forgetting to use absolute value when integrating 1/x . — Always write ∫ (1/x) dx = ln|x| + C to ensure the logarithm is defined for all non-zero values of x .
Where the marks go
- Full worked solution (all marking points)4 marks