Question

[Trần Thị Bích Lam]

Quy đồng mẫu hai phân thức:

a) \(\dfrac{5}{2x+6},\dfrac{3}{x^2-9}\) b)\(\dfrac{2x}{x^2-8x+16},\dfrac{x}{3x^2-12x}\)

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

e)\(\dfrac{1}{x+2},\dfrac{8}{2x-x^2}\) d)\(x^2+1\), \(\dfrac{x^4}{x^2-1}\)

f)\(\dfrac{x^3}{x^3-3x^2y+3xy^2-y^3},\dfrac{x}{y^2-xy}\)

Answer 1

[Nguyễn Lê Phước Thịnh]

a: \(\dfrac{5}{2x+6}=\dfrac{5\left(x-3\right)}{2\left(x+3\right)\left(x-3\right)}\)

3/x^2-9=6/2(x+3)(x-3)

b: \(\dfrac{2x}{x^2-8x+16}=\dfrac{2x}{\left(x-4\right)^2}=\dfrac{6x^2}{3x\left(x-4\right)^2}\)

\(\dfrac{x}{3x^2-12x}=\dfrac{x}{3x\left(x-4\right)}=\dfrac{x\left(x-4\right)}{3x\left(x-4\right)^2}\)

c: \(\dfrac{x+y}{x}=\dfrac{\left(x+y\right)\cdot\left(x-y\right)}{x\left(x-y\right)}\)

x/x-y=x^2/x(x-y)

e: \(\dfrac{1}{x+2}=\dfrac{2x-x^2}{x\left(x+2\right)\left(2-x\right)}\)

\(\dfrac{8}{2x-x^2}=\dfrac{8\left(x+2\right)}{x\left(2-x\right)\left(2+x\right)}\)