x(-9x)=-18x

Solution for x(-9x)=-18x equation:

x(-9x)=-18x

We move all terms to the left:

x(-9x)-(-18x)=0

We multiply parentheses

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