Question

# The term without x in the expansion of (2x−12x2) is

A

495

B

-495

C

-7920

D

7920

Solution

## The correct option is B 7920 Suppose the (r+1)th term in the given expansion is independent of x. Then, we have: Tn+1=12Cr(2x)12−r(−12x2)r =(−1)r12Cr212−2rx12−r−2r For this term to be independent of x, we must have: 12-3r =0 ⇒r=4 ∴ Required term: (−1)412C4212−8 =12×11×10×94×3×2×16 =7920 MathematicsRD SharmaStandard XI

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