if 1−x+x2n=a0+a1x+a2x2+…+a2nx2n then a0+a2+a4+…+a2n is equal to

1−x+x2n=a0+a1x+a2x2+…+a2nx2n on putting X=1, we get(1−1+1)n=a0+a1+a2+…+a2n ⇒ 1=a0+a1+a2+…+a2n  .....(i)Again, putting  x= - 1, we get3n=a0−a1+a2−…+a2n3n+12=a0+a2+a4+…+a2n