$Q5.$ Let a and $bbe$ some unknown positive real numbers. $If$ the following function $is$ continuous $atx=0,$

what $is$ the relationship between a and $b?$

$f(x)=\{\begin{array}{ccc}\frac{sin(ax)}{4x}& if& x<0\\ lo{g}_2(x+8^{x+b})& if& x0\end{array}$