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The coefficient of x^9 in the expansion...

The coefficient of `x^9` in the expansion of `(1+x)(1+ x^2)(1+x^3)....(1+x^(100))` is

Text Solution

Verified by Experts

`x^(9)` can be formed in following eight ways.
i.e, `x^(9), x^(1+8), x^(2+7), x^(3+6), x^(4+5), x^(1+2+6), x^(1+3+5), x^(2+3+4)`
and coefficient in each case is 1.
`:.` Coefficient of `x^(9) = 1+1+1+"……" 8` times
`= 8`
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