F(-4)=5x^2-3x-4

Solution for F(-4)=5x^2-3x-4 equation:

(-4)=5F^2-3F-4

We move all terms to the left:

(-4)-(5F^2-3F-4)=0

We add all the numbers together, and all the variables

-(5F^2-3F-4)-4=0

We get rid of parentheses

-5F^2+3F+4-4=0

We add all the numbers together, and all the variables

-5F^2+3F=0

a = -5; b = 3; c = 0;
Δ = b2-4ac
Δ = 32-4·(-5)·0
Δ = 9
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$F_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$F_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{9}=3$
$F_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(3)-3}{2*-5}=\frac{-6}{-10}
=3/5
$
$F_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(3)+3}{2*-5}=\frac{0}{-10}
=0
$