1.8x^2+4.2x+1.2=0

Solution for 1.8x^2+4.2x+1.2=0 equation:

1.8x^2+4.2x+1.2=0

a = 1.8; b = 4.2; c = +1.2;
Δ = b2-4ac
Δ = 4.22-4·1.8·1.2
Δ = 9
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{9}=3$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4.2)-3}{2*1.8}=\frac{-7.2}{3.6}
=-2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4.2)+3}{2*1.8}=\frac{-1.2}{3.6}
=-1/3
$