解：1因式分解：（1）原式=(x-y)(a+4)(a-4)（2）原式=(x+y)(x-y)(x+y)(x-y)2计算：（1）原式=（-x）^4*x^4*[x^(-2)]^2=x^8*x^(-4)=x^4（2）原式=(-1/2)^(-2)+1+(-5)^3/(-5)^2=4+1-5=0
