Question

Решите ? (у/5х-5х/у): (у+5х) при х=1/7 у=1/4

Answer 1

$( \frac{y}{5x} - \frac{5x}{y} ):(y+5x)= \\ \\ = \frac{y^2-25x^2}{5xy} * \frac{1}{5x+y} = \\ \\ = \frac{(y-5x)(5x+y)}{5xy} * \frac{1}{5x+y} = \\ \\ = \frac{y-5x}{5xy}$
Подставляем значения x и y
$\frac{ \frac{1}{4}-5* \frac{1}{7} }{5* \frac{1}{4} * \frac{1}{7} } = \\ \\ = \frac{ \frac{-13}{28} }{ \frac{5}{28} } = \\ \\ =- \frac{13}{5} = \\ \\ =-2,6$