In the expansion of (x + a)n , if the sum of odd terms be A and the sum of even terms be B, then value of (x2 – a2 )n is
AB
2AB
4AB
A2−B2
We have (x+a)n=A+B and (x−a)n=A−B
∴x2−a2n=(x+a)n(x−a)n=(A+B)(A−B)=A2−B2.