combining like terms

Hi there. Like terms are terms that have the same variable factors. 2x and 2y are not like terms, but 5x and -8x are like terms. x^{2} and x are NOT like terms, because x^{2}=x*x (it has two variable factors). In an expression, find the like terms and add their coefficients to combine like terms.

5x^{2}-6-12x^{2}+12+2x

-7x^{2} + 2x
+ 6

Don't add exponents. Remember that x*x = x^{2} but 2x = x + x.