Question

Упростите выражение, заранее спасибо)

Answer 1

$\frac{x-9y}{x^{2}-9y^{2}} -\frac{3y}{3xy-x^{2} } =\frac{x-9y}{(x-3y)(x+3y)}-\frac{3y}{x(3y-x)} =\frac{x-9y}{(x-3y)(x+3y)} +\frac{3y}{x(x-3y)} =\frac{x^{2}-9xy+3xy+9y^{2}  }{x(x-3y)(x+3y)}=\frac{x^{2}-6xy+9y^{2}}{x(x-3y)(x+3y)}=\frac{(x-3y)^{2} }{x(x-3y)(x+3y)}=\frac{x-3y}{x^{2}+3xy }$