تابع با ضابطهی $f\left( x \right)=\left\{ \begin{matrix} \begin{align} & 2x+3a\,\,\,\,\,\,\,\,\,\,\,\,\,\,x\gt -2 \\ & 2\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x=-2 \\ \end{align} \\ {{x}^{2}}-2bx\,\,\,\,\,\,\,\,\,\,\,x\lt -2 \\\end{matrix} \right.$ در نقطهی $x=-2$ پیوسته است. $a+b$ کدام است؟