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# Binomial expansion a-level maths homework

1. The first 3 terms in the expansion of (1+ax)^n are 1+21x+189x^2. Find the values of a and n.
2. (Original post by Emmaturner45)
The first 3 terms in the expansion of (1+ax)^n are 1+21x+189x^2. Find the values of a and n.
Expand (1+ax)^n using the binomial expansion, then compare coefficients of x and x^2.
You should end up with two equations involving a and n.

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