Multiply x^2 by all terms in the second parenthesis, multiply 2x by all terms in the second parenthesis, then multiply-3 y all terms in the second parenthesis.
4x^4 -5x^3 + 6x^2
8x^3 - 10x^2 + 12x
-12x^2 +15x - 18
Combine like terms
4x*^4 + 3x^3 -16x^2+27x-18
