F(x)=-5x^2+10x+7

Solution for F(x)=-5x^2+10x+7 equation:

(F)=-5F^2+10F+7

We move all terms to the left:

(F)-(-5F^2+10F+7)=0

We get rid of parentheses

5F^2-10F+F-7=0

We add all the numbers together, and all the variables

5F^2-9F-7=0

a = 5; b = -9; c = -7;
Δ = b2-4ac
Δ = -92-4·5·(-7)
Δ = 221
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{-(-9)-\sqrt{221}}{2*5}=\frac{9-\sqrt{221}}{10}
$
$F_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-9)+\sqrt{221}}{2*5}=\frac{9+\sqrt{221}}{10}
$