Question

f (4)=-3×^2-2 g (×)=-2×+2 find f (4) and g (7)

Answer 1

I'm pretty sure you meant:
$f(x) = -3x^2-2$
$g(x) = -2x+2$

To evaluate a function at a certain value, you just have to plug that certain value into the function. Basically, replace all x's with the one given. Let's do f(x) first:
$f(4) = -3(4)^2-2=-3(16)-2 = -48-2 = -50$

So, for f(x), your answer is -50.

Let's do the exact same thing for g(x):
$g(7) = -2(7)+2 = -14+2 = -12$

Your answer for g(x) is -12. 

Hopefully, this makes sense!