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Question: If (1 + x) (1 + x<sup>2</sup>) (1 + x<sup>4</sup>)……(1 + x<sup>128</sup>) = ![](https://cdn.pureesse...

If (1 + x) (1 + x2) (1 + x4)……(1 + x128) = then n is –

A

225

B

255

C

60

D

127

Answer

255

Explanation

Solution

(1 + x) (1 + x2) (1 + x3)…..(1 + x128)

= 1 + x + x2 + ….+ xn

̃ (1 – x) {(1 + x) (1 + x2) (1 + x3)}……(1 + x128)

̃ (1 – x256) = (1 – xn + 1)

̃ n + 1 = 256

n = 225.