F(-2)=6x^2-13x-8

Solution for F(-2)=6x^2-13x-8 equation:

(-2)=6F^2-13F-8

We move all terms to the left:

(-2)-(6F^2-13F-8)=0

We add all the numbers together, and all the variables

-(6F^2-13F-8)-2=0

We get rid of parentheses

-6F^2+13F+8-2=0

We add all the numbers together, and all the variables

-6F^2+13F+6=0

a = -6; b = 13; c = +6;
Δ = b2-4ac
Δ = 132-4·(-6)·6
Δ = 313
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{-(13)-\sqrt{313}}{2*-6}=\frac{-13-\sqrt{313}}{-12}
$
$F_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(13)+\sqrt{313}}{2*-6}=\frac{-13+\sqrt{313}}{-12}
$