Answers

2014-08-08T20:22:19+08:00
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).
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2014-08-08T20:45:23+08:00
  ax-ay-by+bx
=  a(x-y)+b(x-y)        /     -by+bx    =  +(bx-by)
= (x-y)(a+b)          by grouping
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