(i) Given that n is a positive integer, find the first 3 terms in the expansion of (1 + x/2)^n in ascending powers of x.
- (i)Given that n is a positive integer, find the first 3 terms in the expansion of (1 + x/2)^n in ascending powers of x.[2]
- (ii)Given that the coefficient of x² in the expansion of (1 – x)(1 + x/2)^n is 25/4, find the value of n.[5]
Mark scheme
Marking points from the official mark scheme (May/June 2013). The mark or mark type is shown in brackets.
- [1] B1 for 1 + second term
- [1] B1 3rd term Allow unsimplified
- [1] M1 dealing with 2 terms involving x²
- [1] DM1 attempt to obtain one term
- [1] DM1 attempt to obtain a second term
- [1] A1 correct quadratic equation
- [1] A1 for n = 10 only
Write your answer and get it marked
On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.
Sign up free →