Chapter 5 - Exponents and Polynomials - 5.1 - Addition and Subtraction of Polynomials - Problem Set 5.1 - Page 195: 23

$6x^2-5x-4$

We write an expression to express this addition problem: $(2x^2-x+4)+(-5x^2-7x-2)+(9x^2+3x-6)$ We use the commutative and associative properties of addition to group like terms: $(2x^2+(-5x^2)+9x^2)+(-x+(-7x)+3x)+(4+(-2)+(-6))$ We combine the like terms: $6x^2+(-5x)+(-4)=6x^2-5x-4$