-x2+100x-1600=0

Solution for -x2+100x-1600=0 equation:

-x2+100x-1600=0

We add all the numbers together, and all the variables

-1x^2+100x-1600=0

a = -1; b = 100; c = -1600;
Δ = b2-4ac
Δ = 1002-4·(-1)·(-1600)
Δ = 3600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3600}=60$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(100)-60}{2*-1}=\frac{-160}{-2}
=+80
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(100)+60}{2*-1}=\frac{-40}{-2}
=+20
$