3x*(x-1.2)=0

Solution for 3x*(x-1.2)=0 equation:

3x(x-1.2)=0

We multiply parentheses

3x^2-3.6x=0

a = 3; b = -3.6; c = 0;
Δ = b2-4ac
Δ = -3.62-4·3·0
Δ = 12.96
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-3.6)-\sqrt{12.96}}{2*3}=\frac{3.6-\sqrt{12.96}}{6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-3.6)+\sqrt{12.96}}{2*3}=\frac{3.6+\sqrt{12.96}}{6}
$