Expand (x-y)3
Expansion of algebric expression:
We know that (x-y)3 can be written as
(x-y)(x-y)(x-y)
We know that (x-y)(x-y) can be multiplied and written as
x2-xy-yx+y2(x-y)=x2-2xy+y2(x-y)=x3-2x2y+xy2-yx2+2xy2-y3=x3-3x2y+3xy2-y3
Hence,(x-y)3=x3-y3-3x2y+3xy2
If (x+y)3−(x−y)3−6y(x2−y2) = ky2 , then k =