-2x(x-9)=-24

Solution for -2x(x-9)=-24 equation:

-2x(x-9)=-24

We move all terms to the left:

-2x(x-9)-(-24)=0

We add all the numbers together, and all the variables

-2x(x-9)+24=0

We multiply parentheses

-2x^2+18x+24=0

a = -2; b = 18; c = +24;
Δ = b2-4ac
Δ = 182-4·(-2)·24
Δ = 516
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{516}=\sqrt{4*129}=\sqrt{4}*\sqrt{129}=2\sqrt{129}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(18)-2\sqrt{129}}{2*-2}=\frac{-18-2\sqrt{129}}{-4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(18)+2\sqrt{129}}{2*-2}=\frac{-18+2\sqrt{129}}{-4}
$