2(x-y)^2+8(y-x)^2-(y-x)^3+(x-y)^3
=2(x-y)^2+8[-(x-y)]^2-[-(x-y)]^3+(x-y)^3
=2*2^2+8*[-2]^2-[-2]^3+2^3
=8+32+8+8
=64