Question

Найдите значение выражения

Answer 1

$\frac{ x^{2} }{ x^{2} -9xy} : \frac{x}{ x^{2} -81 y^{2} } = \frac{ x^{2} }{x(x-9y)}* \frac{(x-9y)(x+9y)}{x}=x+9y\\\\\\7+9 \sqrt{7}+9(9- \sqrt{7})=7+9 \sqrt{7}+81-9 \sqrt{7}=88$