b:
\(Q=\left(\dfrac{x\left(2-x\right)}{2\left(x^2+4\right)}-\dfrac{2x^2}{\left(x^2+4\right)\left(x-2\right)}\right)\cdot\dfrac{2+x-x^2}{x^2}\)
\(=\dfrac{-x\left(x^2-4x+4\right)-4x^2}{2\left(x^2+4\right)\left(x-2\right)}\cdot\dfrac{-\left(x^2-x-2\right)}{x^2}\)
\(=\dfrac{-x^3+4x^2-4x-4x^2}{2\left(x^2+4\right)}\cdot\dfrac{-\left(x+1\right)}{x^2}\)
\(=\dfrac{-x\left(x^2+4\right)}{2\left(x^2+4\right)}\cdot\dfrac{-\left(x+1\right)}{x^2}=\dfrac{x+1}{x}\)
c: Thay x=2017 vào Q, ta được:
Q=(2017+1)/2017=2018/2017
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