=\(\left(\frac{1}{x\left(x-y\right)}-\frac{3y^2}{x\left(x-y\right)\left(x^2+xy+y^2\right)}-\frac{y}{x\left(x^2+xy+y^2\right)}\right)\)\(\left(\frac{y\left(x+y\right)+x^2}{x+y}\right)\)

=\(\left(\frac{x^2+xy+y^2-3y^2-y\left(x-y\right)}{x\left(x-y\right)\left(x^2+xy+y^2\right)}\right)\) \(\left(\frac{x^2+xy+y^2}{x+y}\right)\)

=\(\left(\frac{x^2+xy-2y^2-xy+y^2}{x\left(x-y\right)}\right)\left(\frac{1}{x+y}\right)\)

=\(\frac{x^2-y^2}{x\left(x-y\right)\left(x+y\right)}\)=\(\frac{\left(x-y\right)\left(x+y\right)}{x\left(x-y\right)\left(x+y\right)}\) =\(\frac{1}{x}\)

quy đồng H lên rồi rút gọn

sau ko rút gọn xong thì tìm x nguyên khi H=6

\(\frac{2}{xy}:\left(\frac{1}{x}-\frac{1}{y}\right)^2-\frac{x^2+y^2}{\left(x-y\right)^2}\left(ĐK:x\ne0;y\ne0\right)\)

\(=\frac{2}{xy}:\left(\frac{y-x}{xy}\right)^2-\frac{x^2+y^2}{\left(x-y\right)^2}\)

\(=\frac{2}{xy}\cdot\frac{x^2y^2}{\left(y-x\right)^2}-\frac{x^2+y^2}{\left(x-y\right)^2}\)

\(=\frac{-2xy}{\left(x-y\right)^2}+\frac{x^2+y^2}{\left(x-y\right)^2}\)

\(=\frac{-2xy+x^2+y^2}{\left(x-y\right)^2}\)

\(=\frac{\left(x-y\right)^2}{\left(x-y\right)^2}=1\)

\(\frac{2}{xy}:\left(\frac{1}{x}-\frac{1}{y}\right)^2-\frac{x^2+y^2}{\left(x-y\right)^2}\left(dk:x\ne y\ne0\right)\)

miik ko nghĩ nó là toán lớp 7 đâu bn

\(\frac{\left(x-y\right)^3-3xy\left(x+y\right)+y^3}{x-6y}\)

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

\(=\frac{x^3-6x^2y}{x-6y}\)

\(=\frac{x^2\left(x-6y\right)}{x-6y}\)

\(=x^2\)

chúc bạn học giỏi 

(x-y)³ - 3xy(x+y) + y³

x - 6y

x³ - 3x²y +3xy² - y³ - 3x²y - 3xy² + y³

x - 6y

x³ - 6x²y

x - 6y

x²(x-6y)

x - 6y

= x²

chắc =1 đó chỉ cần đọc kĩ đề thôi