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IPMAT Indore 2022 - QA (SA) Q5 Explanation

Author : Akash Kumar Singh

December 26, 2024

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Explanation:

(256)

Using Binomial Theorem,

(5x -9)^4 = 4C0 (5x)^4 (-9)0 + 4 4 1 (5x)^3 (-9)^1 + …………+ 4(4(5x)^0(-9)^4

We can obtain sum of coefficients of all the terms in the expansion by substituting x =1 on the RHS.

As RHS equals to LHS, we can get the sum of coefficients even by substituting x = 1 in LHS only.

∴ Put x = 1 in L.H.S expression, we get

(5.1-9)^4 = (-4)^4 = 256