Question

If the first three terms of the expansion of (1+ax)^n in ascending powers of x are 1-4x+7x^2, Find n and a. If the first three terms of the expansion of (1+ax)^n in ascending powers of x are 1-4x+7x^2, Find n and a. @Mathematics

Answer 1

Please Helppp !!

Answer 2

By the binomial expansion, (1+ax)^n = 1+(nC1)ax+(nC2)(ax)^2...

Answer 3

nC1 = n, nC2 = n(n-1)/2

Answer 4

Plugging in the values from the question, na = -4 and a^2(n^2-n)/2 = 7

Answer 5

HEy Moorsy Got it !! Thanks 4 ur help :)

Answer 6

1 more question why u did n(n-1) /2 . why did u divide the whole tern with 2 ??

Answer 7

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