-0.5x^2+5x-8=0

Solution for -0.5x^2+5x-8=0 equation:

-0.5x^2+5x-8=0

a = -0.5; b = 5; c = -8;
Δ = b2-4ac
Δ = 52-4·(-0.5)·(-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{-(5)-3}{2*-0.5}=\frac{-8}{-1}
=+8
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5)+3}{2*-0.5}=\frac{-2}{-1}
=+2
$