F(x)=-x2-2x+20

Solution for F(x)=-x2-2x+20 equation:

(F)=-F2-2F+20

We move all terms to the left:

(F)-(-F2-2F+20)=0

We add all the numbers together, and all the variables

-(-1F^2-2F+20)+F=0

We get rid of parentheses

1F^2+2F+F-20=0

We add all the numbers together, and all the variables

F^2+3F-20=0

a = 1; b = 3; c = -20;
Δ = b2-4ac
Δ = 32-4·1·(-20)
Δ = 89
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{-(3)-\sqrt{89}}{2*1}=\frac{-3-\sqrt{89}}{2}
$
$F_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(3)+\sqrt{89}}{2*1}=\frac{-3+\sqrt{89}}{2}
$