Question

f(x)=3x-1/x-7 determine f(-1/2)²

Answer 1

$f\left(x \right )=3x-\dfrac{1}{x}-7\\ \\ \\ \left[\,f\left(^{-1}\!\!\!\diagup\!\!_{2} \right )\, \right ]^{2}=\left[\,3\cdot \left(\,^{-1}\!\!\!\diagup\!\!_{2} \right )-\dfrac{1}{\,^{-1}\!\!\!\diagup\!\!_{2}}-7\, \right ]^{2}\\ \\ \left[\,f\left(^{-1}\!\!\!\diagup\!\!_{2} \right )\, \right ]^{2}=\left[\,^{-3}\!\!\!\diagup\!\!_{2}+2-7\, \right ]^{2}\\ \\ \left[\,f\left(^{-1}\!\!\!\diagup\!\!_{2} \right )\, \right ]^{2}=\left[\,\dfrac{-3+4-14}{2} \right ]^{2}\\ \\ \left[\,f\left(^{-1}\!\!\!\diagup\!\!_{2} \right )\, \right ]^{2}=\left[\,^{-13}\!\!\!\diagup\!\!_{2} \right ]^{2}\\ \\ \boxed{\left[\,f\left(^{-1}\!\!\!\diagup\!\!_{2} \right )\, \right ]^{2}=\dfrac{169}{4}}$