Question

Выполните сложение и вычитание дробей a) 1/2a+1/a b)3/3-y-y/y^2-9

Answer 1

$frac{1}{2a} + frac{1}{a} = frac{1+1*2}{2a} = frac{3}{2a} \ \ frac{3}{3-y} - frac{y}{y^2-9} = frac{3}{3-y} - frac{y}{-(3^2-y^2)} = frac{3}{3-y} -(- frac{y}{(3-y)(3+y)} )= \ \ = frac{3}{3-y} +frac{y}{(3-y)(3+y)} = frac{3(3+y)+y}{(3-y)(3+y)} = frac{9+3y+y}{9-y^2} = frac{9+4y}{9-y^2} = \ \ = -frac{4y+9}{y^2-9}$