x(12+5x)=0

Solution for x(12+5x)=0 equation:

x(12+5x)=0

We add all the numbers together, and all the variables

x(5x+12)=0

We multiply parentheses

5x^2+12x=0

a = 5; b = 12; c = 0;
Δ = b2-4ac
Δ = 122-4·5·0
Δ = 144
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{144}=12$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(12)-12}{2*5}=\frac{-24}{10}
=-2+2/5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(12)+12}{2*5}=\frac{0}{10}
=0
$