For 50 points can someone explain what i did wrong?

When you plug -x in for x it’ll look like this -(-x)^2 so when you square the -x it doesn’t change the sign of x because of the negative sign outside of the parentheses so it’s still a negative x.
So it’ll look like this
F(x)= -x^2-1
F(-x)= -(-x)^2-1
F(-x)= -x^2-1