X2+2.4x=-0.8

Solution for X2+2.4x=-0.8 equation:

X2+2.4X=-0.8

We move all terms to the left:

X2+2.4X-(-0.8)=0

We add all the numbers together, and all the variables

X^2+2.4X+0.8=0

a = 1; b = 2.4; c = +0.8;
Δ = b2-4ac
Δ = 2.42-4·1·0.8
Δ = 2.56
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{-(2.4)-\sqrt{2.56}}{2*1}=\frac{-2.4-\sqrt{2.56}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2.4)+\sqrt{2.56}}{2*1}=\frac{-2.4+\sqrt{2.56}}{2}
$