## Precalculus: Mathematics for Calculus, 7th Edition

$State$ $the$ $property$ $of$ $real$ $numbers$ $being$ $used:$ $(A+1)(x+y) = (A+1)x + (A+1)y$ We distribute the x and y to $(A+1)$ twice for both terms hence (A+1)x and (A+1)y. This is proven true if we factor the (A+1) which equals (A+1)(x+y).