Question

Номер 9. На картинке все описано.

Answer 1

Ответ:

-11/20

Объяснение:

$\displaystyle\bf\\\frac{xy-y^2}{x^2-xy+4y^2} =\frac{1}{5} \\\\x^2-xy+4y^2=5xy-5y^2\\\\x^2-6xy+9y^2=0\\\\(x-3y)^2=0\\\\x=3y\\\\\frac{2x+5y}{y-7x} =\frac{2\cdot3y+5y}{y-7\cdot3y} =\frac{11y}{-20y} =-\frac{11}{20}$