(3a+1)(4a+8)=0

Solution for (3a+1)(4a+8)=0 equation:

(3a+1)(4a+8)=0

We multiply parentheses ..

(+12a^2+24a+4a+8)=0

We get rid of parentheses

12a^2+24a+4a+8=0

We add all the numbers together, and all the variables

12a^2+28a+8=0

a = 12; b = 28; c = +8;
Δ = b2-4ac
Δ = 282-4·12·8
Δ = 400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{400}=20$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(28)-20}{2*12}=\frac{-48}{24}
=-2
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(28)+20}{2*12}=\frac{-8}{24}
=-1/3
$