Question

cho BT:

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

a) Rut gon A

b)tinh A khi \(x^2-3x+2=0\)

c)tim x de A nguyen

Answer 1

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

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

\(=-x\left(x-1\right)\)

b: x²-3x+2=0

=>(x-2)(x-1)=0

=>x=1(loại) hoặc x=2(nhận)

Khi x=2 thì A=-2