`[(x+2).P]/[x^2-1]=[(x-2)Q]/[x^2-2x+1]`
`<=>[(x+2).P]/[(x-1)(x+1)]=[(x-2).Q]/[(x-1)^2]`
`<=>(x+1)(x-2).Q=(x-1).(x+2).P`
`<=>(x^2-2x+x-2).Q=(x^2+2x-x-2).P`
`<=>(x^2-x-2).Q=(x^2+x-2).P`
`=>{(Q=x^2+x-2),(P=x^2-x-2):}`
\(\Leftrightarrow\dfrac{\left(x+2\right)\cdot P}{\left(x-1\right)\left(x+1\right)}=\dfrac{\left(x-2\right)\cdot Q}{\left(x-1\right)^2}\)
\(\Leftrightarrow P=\dfrac{\left(x-1\right)\left(x+1\right)\cdot\left(x-2\right)\cdot Q}{\left(x+2\right)\cdot\left(x-1\right)^2}=\dfrac{\left(x+1\right)\left(x-2\right)\cdot Q}{\left(x+2\right)\left(x-1\right)}\)
