It is an expression that you factor, not an equation. The expression may be one side of an equation, but it is nottheequation.

Depends on the expression and the numbers. Some are easy and can be done by inspection, some can be done with the rational root theorem, some can be done using the quadratic formula, and some cannot be done in the sense that you are probably thinking of.

Show us what you want to factor and I'm sure that we will show you how to factor thoese that can be factored "nicely".

RonL