Answer:
-9
Step-by-step explanation:
Think intuitively. The expression "g(x) = h(x) + k" simply means x^2 -6 is equal to (x^2 + 3) plus a number. The only number changing is the constant value, and in order to go from 3 to -6, we subtract -9;
x^2 - 6 = (x^2 + 3) - 9
