F(200)=5x2

Solution for F(200)=5x2 equation:

(200)=5F^2

We move all terms to the left:

(200)-(5F^2)=0

a = -5; b = 0; c = +200;
Δ = b2-4ac
Δ = 02-4·(-5)·200
Δ = 4000
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$F_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$F_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{4000}=\sqrt{400*10}=\sqrt{400}*\sqrt{10}=20\sqrt{10}$
$F_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-20\sqrt{10}}{2*-5}=\frac{0-20\sqrt{10}}{-10}
=-\frac{20\sqrt{10}}{-10}
=-\frac{2\sqrt{10}}{-1}
$
$F_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+20\sqrt{10}}{2*-5}=\frac{0+20\sqrt{10}}{-10}
=\frac{20\sqrt{10}}{-10}
=\frac{2\sqrt{10}}{-1}
$