3n(7+4n)=0

Solution for 3n(7+4n)=0 equation:

3n(7+4n)=0

We add all the numbers together, and all the variables

3n(4n+7)=0

We multiply parentheses

12n^2+21n=0

a = 12; b = 21; c = 0;
Δ = b2-4ac
Δ = 212-4·12·0
Δ = 441
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{441}=21$
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(21)-21}{2*12}=\frac{-42}{24}
=-1+3/4
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(21)+21}{2*12}=\frac{0}{24}
=0
$