Question

Сложить:
1. $frac{x-y}{z}- frac{x+y}{z}$
2. $frac{1}{a}+ frac{1}{3a}$

Answer 1

$1) frac{x-y}{z} - frac{x+y}{z} = frac{x-y-(x+y)}{z} = frac{x-y-x-y}{z} = frac{-2y}{z}=- frac{2y}{z} \ \ 2) frac{1}{a} + frac{1}{3a} = frac{3*1}{3a} + frac{1}{3a} = frac{3+1}{3a} = frac{4}{3a}$