[tex] (a)\\f(x)=\dfrac{x}{4}\\\\f\left(\dfrac{1}{2}\right)=\dfrac{\frac{1}{2}}{2}=\dfrac{1}{2\cdot2}=\dfrac{1}{4}\\\\(b)\\\\y=\dfrac{x}{4}\ \ \ \ |\cdot4\\\\4y=x\to f^{-1}(x)=4x [/tex]
