-5x(x+8)=-45

Solution for -5x(x+8)=-45 equation:

-5x(x+8)=-45

We move all terms to the left:

-5x(x+8)-(-45)=0

We add all the numbers together, and all the variables

-5x(x+8)+45=0

We multiply parentheses

-5x^2-40x+45=0

a = -5; b = -40; c = +45;
Δ = b2-4ac
Δ = -402-4·(-5)·45
Δ = 2500
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2500}=50$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-40)-50}{2*-5}=\frac{-10}{-10}
=1
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-40)+50}{2*-5}=\frac{90}{-10}
=-9
$