I'm assuming that you are given the equation f(x) = 2x^2 + 3 and the value f(-3).
To find this, all you need to do is plug in the value of -3 in f(x) for all x values. It would look like:
[tex]f(x) = 2(-3)^{2} + 3[/tex]
All you need to do is simplify:
[tex]f(x) = 2(9) + 3[/tex]
[tex]f(x) = 18 + 3[/tex]
[tex]f(x) = 21[/tex]
Your final answer is f(x) = 21.