F(2)=3x^2+2x-12

Solution for F(2)=3x^2+2x-12 equation:

(2)=3F^2+2F-12

We move all terms to the left:

(2)-(3F^2+2F-12)=0

We get rid of parentheses

-3F^2-2F+12+2=0

We add all the numbers together, and all the variables

-3F^2-2F+14=0

a = -3; b = -2; c = +14;
Δ = b2-4ac
Δ = -22-4·(-3)·14
Δ = 172
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:

$\sqrt{\Delta}=\sqrt{172}=\sqrt{4*43}=\sqrt{4}*\sqrt{43}=2\sqrt{43}$
$F_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-2)-2\sqrt{43}}{2*-3}=\frac{2-2\sqrt{43}}{-6}
$
$F_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2)+2\sqrt{43}}{2*-3}=\frac{2+2\sqrt{43}}{-6}
$