# Thread: Factoring guidelines needed

1. ## Factoring guidelines needed

Since the original problem must be equivalent to the book answer, if I develop both sides, the final products have to be equivalent expressions. That’s the theory. As I haven’t been able to go from the original problem to the book answer, I decided to solve both sides to see were is my problem, but I can’t see what I’m doing wrong.

2. Originally Posted by Alienis Back
Since the original problem must be equivalent to the book answer, if I develop both sides, the final products have to be equivalent expressions. That’s the theory. As I haven’t been able to go from the original problem to the book answer, I decided to solve both sides to see were is my problem, but I can’t see what I’m doing wrong.
In all three questions the procedure is the same: The common factor of the summands is the sum in brackets:

If you factor out a term you have to divide each summand by this term.

$5x(a-2b)-3y(a-2b) = (a-2b)\left(\frac{5x(a-2b)}{a-2b}-\frac{3y(a-2b)}{a-2b} \right)= (a-2b)(5x-3y)$

The other 2 problems could be dome similarily(?).