Evaluate a2 + b for a = and b = -.

To evaluate a2+b, just solve for a and b:

a2+b=0 subt. b from both sides

a2=-b now find the sq. root of both sides

a=sq rt of - b

a2+b=0 subt. - a2 from both sides

b = - a2

I hope this is what you were looking for. If not, then sorry.