Question

Answer 1

a, đk : x khác -1 ; 1 ; 0 ; 2 

\(A=\left(\dfrac{x^2+2x+1-4-\left(x-1\right)^2}{\left(x-1\right)\left(x+1\right)}\right):\dfrac{\left(x-2\right)^2}{x\left(x+1\right)}\)

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

\(=\dfrac{4\left(x-1\right)x\left(x+1\right)}{\left(x-1\right)\left(x+1\right)\left(x-2\right)^2}=\dfrac{4x}{\left(x-2\right)^2}\)

b, Thay x = 1/2 vào ta được \(\dfrac{2}{\left(\dfrac{1}{2}-2\right)^2}=\dfrac{8}{9}\)