x^2 +ax+b=(x+2)^2-3
\(\begin{array}{|rcll|} \hline x^2 +ax+b &=& (x+2)^2-3 \\ &=& x^2+4x+4-3 \\ &=& x^2+\underbrace{4}_{=a}x+\underbrace{1}_{=b} \\ \hline \end{array}\)
a=4 and b=1
