-x^2+3,5x-1,5=0

Solution for -x^2+3,5x-1,5=0 equation:

-x^2+3.5x-1.5=0

We add all the numbers together, and all the variables

-1x^2+3.5x-1.5=0

a = -1; b = 3.5; c = -1.5;
Δ = b2-4ac
Δ = 3.52-4·(-1)·(-1.5)
Δ = 6.25
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{-(3.5)-\sqrt{6.25}}{2*-1}=\frac{-3.5-\sqrt{6.25}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(3.5)+\sqrt{6.25}}{2*-1}=\frac{-3.5+\sqrt{6.25}}{-2}
$