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If (1+x)(1+x^2)(1+x^4)….(1+x^(128))=Sigm...

If `(1+x)(1+x^2)(1+x^4)….(1+x^(128))=Sigma_(r=0)^(n) x^r`, then n is equal is

A

256

B

255

C

254

D

none of these

Text Solution

Verified by Experts

The correct Answer is:
B

Degree of x on L.H.S is
1+2+4+…+128=`1+2+2^(2)+….+2^(7)`
`=(2^(8)-1)/(2-1)=255`
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