Find a & b for given piecewise functions for being differentiable: $($K$/4,$ C$/2)$

a$)f(x)=\{\begin{array}{cc}\sqrt[3]{(2x+6{)}^2},& x1\\ a{x}^2+bx,& x>1\end{array}$

b$)g(x)=\{\begin{array}{cc}a{e}^{5x}-1,& x0\\ b\sqrt[\phantom{2}]{x+4},& x>0\end{array}$

In $f(x)=\frac{-3x}{x^2+4}$ find critical, extremum and inflection pants use first derivative test for finding Max & min and graph the function: $(\frac{K}{4},\frac{C}{2})$