we have that
2x²-3x-6=0
using a graph tool----------> to resolve the second order equation
see the attached figure
the solution is
x=-1.137
x=2.637
therefore
a=-1.137
b=2.637
so
(a+2)*(b+2)-----------> (-1.137+2)*(2.637+2)--------> 0.863*4.637---> 4
the answer is 4