Section $6$: Differentiation

Evaluate the derivative for the following functions:

$($a$)f(x)=\frac{5}{x^2}-lo{g}_2(7x)$

$($b$)g(x)=e^{-x^2+cosx}+co{t}^{-1}(x).$

$($c$)j(x)=ln(x^3)-ta{n}^{2}x$

$($d$)k(x)=2^x\sqrt[\phantom{2}]{5x+1}$