-0.2x^2+1.4x+8=0

Solution for -0.2x^2+1.4x+8=0 equation:

-0.2x^2+1.4x+8=0

a = -0.2; b = 1.4; c = +8;
Δ = b2-4ac
Δ = 1.42-4·(-0.2)·8
Δ = 8.36
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{-(1.4)-\sqrt{8.36}}{2*-0.2}=\frac{-1.4-\sqrt{8.36}}{-0.4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1.4)+\sqrt{8.36}}{2*-0.2}=\frac{-1.4+\sqrt{8.36}}{-0.4}
$