Question

in the binomial expansion of (2-3/x)^8, find the coefficient of x^-4.

Answer 1

Given binomial expansion of (2-3/x)^8
=>(2x-3)^8/x^8
=>6561/x^8-34992/x^7+81648/x^6-108864/x^5+90720/x^4-48384/x^3+16128/x^2-3072/x+256
hence x^-4 coefficient =90720

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Answer 2

90720......the expansion of it looks like this 6561/x^8-34992/x^7+81648/x^6-108864/x^5+90720/x^4-48384/x^3+16128/x^2-3072/x+256