(s-3)(3s+6)=0

Solution for (s-3)(3s+6)=0 equation:

(s-3)(3s+6)=0

We multiply parentheses ..

(+3s^2+6s-9s-18)=0

We get rid of parentheses

3s^2+6s-9s-18=0

We add all the numbers together, and all the variables

3s^2-3s-18=0

a = 3; b = -3; c = -18;
Δ = b2-4ac
Δ = -32-4·3·(-18)
Δ = 225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$s_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$s_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{225}=15$
$s_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-3)-15}{2*3}=\frac{-12}{6}
=-2
$
$s_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-3)+15}{2*3}=\frac{18}{6}
=3
$