(3a+6)(4a-16)=0

Solution for (3a+6)(4a-16)=0 equation:

(3a+6)(4a-16)=0

We multiply parentheses ..

(+12a^2-48a+24a-96)=0

We get rid of parentheses

12a^2-48a+24a-96=0

We add all the numbers together, and all the variables

12a^2-24a-96=0

a = 12; b = -24; c = -96;
Δ = b2-4ac
Δ = -242-4·12·(-96)
Δ = 5184
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{5184}=72$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-24)-72}{2*12}=\frac{-48}{24}
=-2
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-24)+72}{2*12}=\frac{96}{24}
=4
$