F(x)=3x^2+2,x=3

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

(F)=3F^2+2.F=3

We move all terms to the left:

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

We get rid of parentheses

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

We add all the numbers together, and all the variables

-3F^2-1F=0

a = -3; b = -1; c = 0;
Δ = b2-4ac
Δ = -12-4·(-3)·0
Δ = 1
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$F_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$F_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

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