F(x)=x2+3x=

Solution for F(x)=x2+3x= equation:

(F)=F2+3F=

We move all terms to the left:

(F)-(F2+3F)=0

We add all the numbers together, and all the variables

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

We get rid of parentheses

-F^2-3F+F=0

We add all the numbers together, and all the variables

-1F^2-2F=0

a = -1; b = -2; c = 0;
Δ = b2-4ac
Δ = -22-4·(-1)·0
Δ = 4
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$F_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$F_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4}=2$
$F_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-2)-2}{2*-1}=\frac{0}{-2}
=0
$
$F_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2)+2}{2*-1}=\frac{4}{-2}
=-2
$