2.7x^2+4.2X+0.8=0

Solution for 2.7x^2+4.2X+0.8=0 equation:

2.7x^2+4.2x+0.8=0

a = 2.7; b = 4.2; c = +0.8;
Δ = b2-4ac
Δ = 4.22-4·2.7·0.8
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*2.7}=\frac{-7.2}{5.4}
=-1+1/3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4.2)+3}{2*2.7}=\frac{-1.2}{5.4}
=-1/4.5
$