0=9x2+18x

Solution for 0=9x2+18x equation:

0=9x^2+18x

We move all terms to the left:

0-(9x^2+18x)=0

We add all the numbers together, and all the variables

-(9x^2+18x)=0

We get rid of parentheses

-9x^2-18x=0

a = -9; b = -18; c = 0;
Δ = b2-4ac
Δ = -182-4·(-9)·0
Δ = 324
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{324}=18$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-18)-18}{2*-9}=\frac{0}{-18}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-18)+18}{2*-9}=\frac{36}{-18}
=-2
$