(2х+1)²=2х²+7
4х² + 4х + 1 - 2х² - 7 = 0
2х² + 4х -6 = 0
х² + 2х - 3 = 0
х₁ = -3 х₂ = 1
(y/5x-5x/y):(y+5x) = ((у² - 25х²)/5ху)(1/(y+5x)) = (y-5x)/5xy
Если х=1/5,у=1/4, то (1/4-5*1/5)/5*1/5*1/4 = - 3
