Binomial TheoremHard
Question
The coefficient of x4 in 
, | x | < 1, is
, | x | < 1, isOptions
A.4
B.-4
C.10 + 4C2
D.16
Solution
(1 + x)2 (1 - x)-2
= (1 + x2 + 2x) (1 - x)-2
Co-efficient of x4 = 5C4 + 3C2 + 2 4C3 = 16
= (1 + x2 + 2x) (1 - x)-2
Co-efficient of x4 = 5C4 + 3C2 + 2 4C3 = 16
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