Find the values of a\displaystyle {a} and b\displaystyle {b}, given the polynomial function f(x)=ax4+4x338x264x+b\displaystyle {f{{\left({x}\right)}}}={a}{x}^{{4}}+{4}{x}^{{3}}-{38}{x}^{{2}}-{64}{x}+{b} such that f(x)\displaystyle {f{{\left({x}\right)}}} passes through the point (2,72)\displaystyle {\left(-{2},{72}\right)} and has x=4\displaystyle {x}=-{4} as a zero.

 a=\displaystyle {a}= 

 b=\displaystyle {b}=