F(x)=20x^2-20

Solution for F(x)=20x^2-20 equation:

(F)=20F^2-20

We move all terms to the left:

(F)-(20F^2-20)=0

We get rid of parentheses

-20F^2+F+20=0

a = -20; b = 1; c = +20;
Δ = b2-4ac
Δ = 12-4·(-20)·20
Δ = 1601
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$F_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$F_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$F_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(1)-\sqrt{1601}}{2*-20}=\frac{-1-\sqrt{1601}}{-40}
$
$F_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+\sqrt{1601}}{2*-20}=\frac{-1+\sqrt{1601}}{-40}
$