Find a\displaystyle {a} and b\displaystyle {b} such that
f(x)=x2+ax+b\displaystyle {f{{\left({x}\right)}}}={x}^{{2}}+{a}{x}+{b}
has an average value of 403\displaystyle \frac{{40}}{{3}} over [0,1] and an average value of 283\displaystyle \frac{{28}}{{3}} over [0,4].

a\displaystyle {a} =  
b\displaystyle {b} =