-x^2-1,5x+8=0

Solution for -x^2-1,5x+8=0 equation:

-x^2-1.5x+8=0

We add all the numbers together, and all the variables

-1x^2-1.5x+8=0

a = -1; b = -1.5; c = +8;
Δ = b2-4ac
Δ = -1.52-4·(-1)·8
Δ = 34.25
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{-(-1.5)-\sqrt{34.25}}{2*-1}=\frac{1.5-\sqrt{34.25}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1.5)+\sqrt{34.25}}{2*-1}=\frac{1.5+\sqrt{34.25}}{-2}
$