(x+5)(-2x-3)=0

Solution for (x+5)(-2x-3)=0 equation:

(x+5)(-2x-3)=0

We multiply parentheses ..

(-2x^2-3x-10x-15)=0

We get rid of parentheses

-2x^2-3x-10x-15=0

We add all the numbers together, and all the variables

-2x^2-13x-15=0

a = -2; b = -13; c = -15;
Δ = b2-4ac
Δ = -132-4·(-2)·(-15)
Δ = 49
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{49}=7$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-13)-7}{2*-2}=\frac{6}{-4}
=-1+1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-13)+7}{2*-2}=\frac{20}{-4}
=-5
$