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If the coefficient of (2r+4)th and (r-2)...

If the coefficient of `(2r+4)th` and `(r-2)th` terms in the expansion of `(1+x)^(18)` are equal, find `r` .

A

4

B

5

C

6

D

7

Text Solution

Verified by Experts

In the expansion of `(1+x)^{18}`

coefficient of `T_(2r+4)=18 _(C_(2 r+3))`

coefficient of `T_(r-2)=18_( C_(r_3))`

Given,

`18_( C_(2 r+3))=18_( C_(T-3))`

...
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