Question

Answer 1

a, đk x khác -1 ; 2 

\(A=\dfrac{x-11-x\left(x-2\right)+\left(2x-1\right)\left(x+1\right)}{\left(x-2\right)\left(x+1\right)}\)

\(=\dfrac{x-11-x^2+2x+2x^2+x-1}{\left(x-2\right)\left(x+1\right)}=\dfrac{x^2+4x-12}{\left(x-2\right)\left(x+1\right)}=\dfrac{x+6}{x+1}\)

b, \(x\left(x-2\right)=0\Leftrightarrow x=0\left(tm\right);x=2\left(ktm\right)\)

Thay x = 0 vào ta được \(A=6\)

 c, \(\dfrac{x+6}{x+1}-1\le0\Leftrightarrow\dfrac{x+6-x-1}{x+1}\le0\Leftrightarrow\dfrac{5}{x+1}\le0\)

\(\left\{{}\begin{matrix}5\ne0\left(luondung\right)\\x+1>0\end{matrix}\right.\Leftrightarrow x>-1\)

Kết hợp đk vậy x > -1 ; x khác 2