X

The only factor of x

The factors of 4x are 4 and x.

The only common factor of the two terms is x. When this is extracted from both terms it leaves the remaining factor for the original expression, namely x - 4.

^{2 }- 4x = x(x - 4)The only factor of x

^{2 }is x.The factors of 4x are 4 and x.

The only common factor of the two terms is x. When this is extracted from both terms it leaves the remaining factor for the original expression, namely x - 4.