Math basics › Algebra basics
Factoring
Take out the common factor first
Always. 2x² + 6x = 2x(x + 3). It often makes what is left much easier.
x² + bx + c
Find two numbers that multiply to c and add to b. That is the whole search.
Difference of two squares
a² − b² = (a + b)(a − b). Worth recognising on sight. a² + b² does not factor over the reals.
Check by expanding
Multiply your factors back out. If you do not get what you started with, the factoring is wrong.