9x(9-x)=0

Solution for 9x(9-x)=0 equation:

9x(9-x)=0

We add all the numbers together, and all the variables

9x(-1x+9)=0

We multiply parentheses

-9x^2+81x=0

a = -9; b = 81; c = 0;
Δ = b2-4ac
Δ = 812-4·(-9)·0
Δ = 6561
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{6561}=81$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(81)-81}{2*-9}=\frac{-162}{-18}
=+9
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(81)+81}{2*-9}=\frac{0}{-18}
=0
$