F(-3)=-3x^2+14x+2

Solution for F(-3)=-3x^2+14x+2 equation:

(-3)=-3F^2+14F+2

We move all terms to the left:

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

We add all the numbers together, and all the variables

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

We get rid of parentheses

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

We add all the numbers together, and all the variables

3F^2-14F-5=0

a = 3; b = -14; c = -5;
Δ = b2-4ac
Δ = -142-4·3·(-5)
Δ = 256
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$F_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$F_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{256}=16$
$F_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-14)-16}{2*3}=\frac{-2}{6}
=-1/3
$
$F_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-14)+16}{2*3}=\frac{30}{6}
=5
$