\(a,\dfrac{1}{2x+4}=\dfrac{x-2}{2\left(x+2\right)\left(x-2\right)};\dfrac{x}{2x-4}=\dfrac{x\left(x+2\right)}{2\left(x-2\right)\left(x+2\right)}\\ \dfrac{3}{4-x^2}=\dfrac{-6}{2\left(x-2\right)\left(x+2\right)}\\ b,\dfrac{1}{x-2x^2}=\dfrac{-\left(2x+1\right)}{x\left(2x-1\right)\left(2x+1\right)}\\ \dfrac{20}{4x^3-x}=\dfrac{20}{x\left(2x-1\right)\left(2x+1\right)}\\ \dfrac{7}{2x^2+x}=\dfrac{7\left(2x-1\right)}{x\left(2x+1\right)\left(2x-1\right)}\\ c,\dfrac{x}{x^3+1}=\dfrac{x^2}{x\left(x+1\right)\left(x^2-x+1\right)}\\ \dfrac{x+1}{x^2+x}=\dfrac{\left(x+1\right)\left(x^2-x+1\right)}{x\left(x+1\right)\left(x^2-x+1\right)}\\ \dfrac{x+2}{x^2-x+1}=\dfrac{x\left(x+1\right)\left(x+2\right)}{x\left(x+1\right)\left(x^2-x+1\right)}\)
