## Thinking Mathematically (6th Edition)

-8$x^{2}$ + 10x
3(-4$x^{2}$ + 5x) - (5x - 4$x^{2}$) Use the distributive property to remove the parentheses =3.-4$x^{2}$ + 3.5x - (5x - 4$x^{2}$) Drop parentheses and change the sign of each term in parentheses: - (5x - 4$x^{2}$) = - 5x + 4$x^{2}$ = 3.-4$x^{2}$ + 3.5x - 5x + 4$x^{2}$ Multiply = -12$x^{2}$ + 15x - 5x + 4$x^{2}$ Group like terms = (-12$x^{2}$ + 4$x^{2}$) + (15x - 5x) combine like terms (-12$x^{2}$ + 4$x^{2}$) = (-12+4)$x^{2}$ = -8$x^{2}$, (15x - 5x) =(15 - 5)x = 10x =-8$x^{2}$ + 10x