What methods can be used to solve quadratic equations?

For any of the following methods, first make sure that all terms of the equation are on the left of the equal sign; on the right, there should only be a zero. Thus, for example,

x2 - 5x = 10

becomes:

x2 - 5x - 10 = 0

The methods commonly used are:

1) Factor the polynomial. Sometimes this can be done easily; but if this is too difficult, use one of the other methods below.

2) Complete the square. Add a constant term to both sides of the equation, such that the polynomial on the left becomes a perfect square.

3) Use the quadratic formula. This is usually the simplest method, if you can't find an obvious factorization quickly.