if n is an even integer and a,b,c are disinct terms,in the expansion of(a+b+c)^n+(a-b-c)^n, is (a)n^2-1 (b)(n^2-1)/2 (c)((n+1))^2/4) (d)(n+2)^2/4
if n is an even integer and a,b,c are disinct terms,in the expansion of(a+b+c)^n+(a-b-c)^n, is (a)n^2-1 (b)(n^2-1)/2 (c)((n+1))^2/4) (d)(n+2)^2/4