Answer:
x= 1.3
Explanation:
You have to plug in 7 so it will look like:
f(x) = -2x² + 4
7(x) = -2x² +4
now what you have to do is multiply 7 by x which will get you
7x = -2x² + 4
now because you have that you want to multiply -2 twice because you have that ²
7x = 4x +4
now you want to move the 4x and you can do that by doing the inverse operation and in this case since its a positive 4 you may want to subtract 4x from 4x and 7x
3x=4
now you want to divide 4 from 3 and you get 1.333333333333333
hope this helps