Let f(x) = (4 – x + x²) / ((1+x)(2 + x²))
- (a)Express f(x) in partial fractions.[5]
- (b)Find the exact value of ∫(from 0 to 4) f(x) dx. Give your answer as a single logarithm.[5]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2022). The mark or mark type is shown in brackets.
- [B1] (a) State or imply the form A/(1+x) + (Bx+C)/(2+x²)
- [M1] (a) Use a correct method for finding a constant
- [A1] (a) Obtain one of A = 2, B = -1 and C = 0
- [A1] (a) Obtain a second value
- [A1] (a) Obtain the third value
- [B1 FT] (b) Integrate and obtain term 2ln(1+x)
- [*M1] (b) Integrate and obtain term of the form kln(2+x²) from an integral of the correct form
- [A1 FT] (b) Obtain term -½ln(2+x²)
- [DM1] (b) Substitute limits in an integral containing terms of the form aln(1+x)+bln(2+x²), where ab ≠ 0
- [A1] (b) Obtain answer ln(25/3)
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