a: ĐKXĐ: \(x\notin\left\{0;1;-1\right\}\)
b: \(C=\dfrac{x^2+x}{x^2-2x+1}:\left(\dfrac{x+1}{x}+\dfrac{1}{x-1}+\dfrac{2-x^2}{x^2-x}\right)\)
\(=\dfrac{x\left(x+1\right)}{\left(x-1\right)^2}:\dfrac{\left(x+1\right)\left(x-1\right)+x+2-x^2}{x\left(x-1\right)}\)
\(=\dfrac{x\left(x+1\right)}{\left(x-1\right)^2}\cdot\dfrac{x\left(x-1\right)}{x^2-1+x+2-x^2}\)
\(=\dfrac{x^2\left(x+1\right)}{\left(x-1\right)\cdot\left(x+1\right)}=\dfrac{x^2}{x-1}\)
c: C=-1/2
=>\(\dfrac{x^2}{x-1}=\dfrac{-1}{2}\)
=>\(2x^2=-x+1\)
=>\(2x^2+x-1=0\)
=>(x+1)(2x-1)=0
=>\(\left[{}\begin{matrix}x=-1\left(loại\right)\\x=\dfrac{1}{2}\left(nhận\right)\end{matrix}\right.\)
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