## Precalculus: Mathematics for Calculus, 7th Edition

a.) when subtracting, the Commutative Property cannot be applied. Ex.) 3-5 = 5-3 -2 $\ne$ 2 The left side equals -2 since 3-5 = -2. The right side, however, equals 2 since 5-3 = 2. Therefore: a-b $\ne$ b-a b.) We first use the Distributive Property -2(a-5) = -2a-2(-5) If a minus sign is next to a set of parenthesis, we can then distribute it as a -1. -2a+10 We then determine that it cannot equal -2a-10. -2a+10 $\ne$ 2a-10