3(a+2)(a-8)=0

Solution for 3(a+2)(a-8)=0 equation:

3(a+2)(a-8)=0

We multiply parentheses ..

3(+a^2-8a+2a-16)=0

We multiply parentheses

3a^2-24a+6a-48=0

We add all the numbers together, and all the variables

3a^2-18a-48=0

a = 3; b = -18; c = -48;
Δ = b2-4ac
Δ = -182-4·3·(-48)
Δ = 900
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{900}=30$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-18)-30}{2*3}=\frac{-12}{6}
=-2
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-18)+30}{2*3}=\frac{48}{6}
=8
$