(x)=x2+9x

Solution for (x)=x2+9x equation:

(x)=x2+9x

We move all terms to the left:

(x)-(x2+9x)=0

We add all the numbers together, and all the variables

-(+x^2+9x)+x=0

We get rid of parentheses

-x^2-9x+x=0

We add all the numbers together, and all the variables

-1x^2-8x=0

a = -1; b = -8; c = 0;
Δ = b2-4ac
Δ = -82-4·(-1)·0
Δ = 64
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{64}=8$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-8)-8}{2*-1}=\frac{0}{-2}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8)+8}{2*-1}=\frac{16}{-2}
=-8
$