Question

[bella nguyen]

Thực hiện phép tính

a, x^2 + y^2 - xy/ x^2 + y^2+ 2xy × x^2 + 3xy + 2y^2 / x^2 - 3xy + 2y^2

b, x^2 + 1/3x ÷ x^2 + 1/x - 1 : x^3 -1/x^2 + x ÷ x^2 + 2x + 1/ x^2 +x +1

Answer 1

[Nguyễn Lê Phước Thịnh]

a: \(\dfrac{x^2-xy+y^2}{x^2+2xy+y^2}\cdot\dfrac{x^2+3xy+2y^2}{x^2-3xy+2y^2}\)

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

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

b: \(\dfrac{x^2+1}{3x}:\dfrac{x^2+1}{x-1}:\dfrac{x^3-1}{x^2+x}:\dfrac{x^2+2x+1}{x^2+x+1}\)

\(=\dfrac{x-1}{3x}\cdot\dfrac{x\left(x+1\right)}{\left(x-1\right)\left(x^2+x+1\right)}\cdot\dfrac{x^2+x+1}{\left(x+1\right)^2}\)

\(=\dfrac{x\left(x+1\right)}{3x\left(x+1\right)^2}=\dfrac{1}{3\left(x+1\right)}\)