9x2=-72x

Solution for 9x2=-72x equation:

9x^2=-72x

We move all terms to the left:

9x^2-(-72x)=0

We get rid of parentheses

9x^2+72x=0

a = 9; b = 72; c = 0;
Δ = b2-4ac
Δ = 722-4·9·0
Δ = 5184
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{5184}=72$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(72)-72}{2*9}=\frac{-144}{18}
=-8
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(72)+72}{2*9}=\frac{0}{18}
=0
$