Question

Help me m.n ơi !!!

Answer 1

a: \(A=\left(\dfrac{-1}{x-1}+\dfrac{2}{x+1}-\dfrac{x-5}{\left(x-1\right)\left(x+1\right)}\right):\dfrac{1-2x}{\left(x-1\right)\left(x+1\right)}\)

\(=\dfrac{-x-1+2x-2-x+5}{\left(x-1\right)\left(x+1\right)}\cdot\dfrac{\left(x-1\right)\left(x+1\right)}{1-2x}\)

\(=\dfrac{2}{1-2x}\)

b: Để A là số nguyên thì \(2x-1\inƯ\left(-2\right)\)

\(\Leftrightarrow2x-1\in\left\{1;-1\right\}\)

\(\Leftrightarrow x\in\left\{1;0\right\}\)

Kết hợp ĐKXĐ, ta được: x=0

c: Để |A|=A thì A>=0

=>1-2x>0

=>2x<1

hay x<1/2