Giải toán 8 tập 1: Câu 7 sgk trang 39

a) \(\dfrac{6x^2y^2}{8xy^5} = \dfrac{2.3.x.x.y^2}{2.4.x.y^2.y^3} = \dfrac{3x}{4y^3}\)

b) \(\dfrac{10xy^2(x + y)}{15xy(x + y)^3} \)
\(= \dfrac{2.5xy.y(x + y)}{3.5xy(x + y)^2.(x + y)} \)
\(= \dfrac{2y}{3(x + y)^2}\)

c) \(\dfrac{2x^2 + 2x}{x + 1} = \dfrac{2x(x + 1)}{x + 1} = 2x\)

d) \(\dfrac{x^2 - xy - x + y}{x^2 + xy - x - y}\)
\(= \dfrac{(x^2 - x) - (xy - y)}{(x^2 - x) + (xy - y)}\)
\(= \dfrac{x(x - 1) - y(x - 1)}{x(x - 1) + y(x - 1)}\)
\(= \dfrac{(x - 1)(x - y)}{(x - 1)(x + y)}\)
\(= \dfrac{x - y}{x + y}\)