Sagot :
We first group the similar terms; First, by grouping in A and B: A(X - Y) + B(X - Y), Then we see that (X - Y) is similar in both A and B, we separate (X - Y) --> (X - Y)(A + B).
ax-ay-by+bx
= a(x-y)+b(x-y) / -by+bx = +(bx-by)
= (x-y)(a+b) by grouping
= a(x-y)+b(x-y) / -by+bx = +(bx-by)
= (x-y)(a+b) by grouping