## Functions Modeling Change: A Preparation for Calculus, 5th Edition

$$-3x^{2}-4xa-a^{2}$$
Initial: $x^{2}-(2x+a)^{2}$ First, rewrite the $(2x+a)^{2}$ in its expanded form: $(2x+a)(2x+a)$ Then FOIL it: $$x^{2}-(4x^{2}+4xa+a^{2})$$ After that, distribute the negative: $$x^{2}-4x^{2}-4xa-a^{2}$$ Then simplify by combining like terms: $$-3x^{2}-4xa-a^{2}$$