Question

# If the absolute term (independent of x) in the expansion of (√x−kx2)10 is 405 then k =

A

B

C

D

Solution

## The correct option is B r=10×1212+2=105=2 ∴ Term independent of x is 10C2(−k)2=45k2.   ∴45k2=405⇒k2=9⇒k=±3

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