Download the app

Questions  

If O  be the sum of odd terms and  E that of even terms in the expansion of  (x+a)n,then O2E2=

a
x2+a2n
b
x2−a2n
c
(x−a)2n
d
none of these

detailed solution

Correct option is B

we have , (x+a)n=nC0xna0+nC1xn−1a1+nC2xn−2a2+…+nCn−1xan−1+nCnan⇒(x+a)n= nC0xna0+nC2xn−2a2+…+ nC1xn−1a1+nC3xn−3a3+…⇒(x+a)n=O+E                           (i)and , (x−a)n=nC0xn−nC1xn−1a1+nC2xn−2a2−nC3xn−3a3+…+nCn−1x(−1)n−1an−1+nCn(−1)nan⇒(x−a)n= nC0xn+nC2xn−2a2+…− nC1xn−1a1+nC3xn−3a3+…⇒(x−a)n=O−E                          (ii)From (i) and (ii), we get x+ain(x−a)n=(O+E)(O−E)⇒x2−a2n=O2−E2

Talk to our academic expert!

+91

Are you a Sri Chaitanya student?


Similar Questions

The coefficient of x7 in the expression (1+x)10+x(1+x)9+x2(1+x)8++x10 is


phone icon
whats app icon