-4x(x-9)=-8

Solution for -4x(x-9)=-8 equation:

-4x(x-9)=-8

We move all terms to the left:

-4x(x-9)-(-8)=0

We add all the numbers together, and all the variables

-4x(x-9)+8=0

We multiply parentheses

-4x^2+36x+8=0

a = -4; b = 36; c = +8;
Δ = b2-4ac
Δ = 362-4·(-4)·8
Δ = 1424
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:

$\sqrt{\Delta}=\sqrt{1424}=\sqrt{16*89}=\sqrt{16}*\sqrt{89}=4\sqrt{89}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(36)-4\sqrt{89}}{2*-4}=\frac{-36-4\sqrt{89}}{-8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(36)+4\sqrt{89}}{2*-4}=\frac{-36+4\sqrt{89}}{-8}
$