Đáp án + Giải thích các bước giải:
c)
`(\frac{x}{xy - y²} + \frac{2x-y}{xy - x²}) . \frac{x²y - xy²}{x² - 2xy + y²}`
`= (\frac{x}{y(x-y)} - \frac{2x - y}{x(x-y)}) . \frac{x²y - xy²}{x² - 2xy + y²}`
`= (\frac{x²}{xy(x-y)} - \frac{y(2x - y)}{xy(x-y)}. \frac{x²y - xy²}{x² - 2xy + y²}`
`= \frac{x² - 2xy + y²}{xy(x-y)} . \frac{x²y - xy²}{x² - 2xy + y²}`
`= \frac{(x-y)²}{xy(x-y)} . \frac{x²y - xy²}{x² - 2xy + y²}`
`= \frac{x-y}{xy} . \frac{xy(x-y)}{(x-y)²}`
`= 1`
