Question

решить алгебру 8 класс срочно!

Answer 1

$frac{2a-k}{55k} + frac{k-3a}{22k}= frac{2(2a-k)+5(k-3a)}{110k} = frac{4a-2k+5k-15a}{110k} = frac{3k-11a}{110k}$

2.
$frac{3a^{2}}{ab-4b^{2}}- frac{12a}{a-4b}= frac{3a^{2}-12ab}{b(a-4b)}= frac{3a(a-4b)}{b(a-4b)}= frac{3a}{b}$

3.
$frac{x-15y}{ x^{2} -25y^{2} } - frac{5y}{5xy- x^{2}} = frac{x-15y}{(x-5y)(x+5y)} - frac{5y}{x(5y-x)}= frac{x-15y}{(x-5y)(x+5y)}+ frac{5y}{x(x-5y)} =frac{x(x-15y)+5y(x+5y)}{x(x-5y)(x+5y)}= frac{ x^{2} -15xy+5xy+25y^{2} }{x(x-5y)(x+5y)}= frac{ x^{2}-10xy+25y^{2} }{x(x-5y)(x+5y)}= frac{(x-5y)(x-5y)}{x(x-5y)(x+5y)} = frac{x-5y}{ x(x+5y)}$