(x+0.75)(x+5)=0

Solution for (x+0.75)(x+5)=0 equation:

(x+0.75)(x+5)=0

We multiply parentheses ..

(+x^2+5x+0.75x+3.75)=0

We get rid of parentheses

x^2+5x+0.75x+3.75=0

We add all the numbers together, and all the variables

x^2+5.75x+3.75=0

a = 1; b = 5.75; c = +3.75;
Δ = b2-4ac
Δ = 5.752-4·1·3.75
Δ = 18.0625
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(5.75)-\sqrt{18.0625}}{2*1}=\frac{-5.75-\sqrt{18.0625}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5.75)+\sqrt{18.0625}}{2*1}=\frac{-5.75+\sqrt{18.0625}}{2}
$