-x^2+665x-9750=0

Solution for -x^2+665x-9750=0 equation:

-x^2+665x-9750=0

We add all the numbers together, and all the variables

-1x^2+665x-9750=0

a = -1; b = 665; c = -9750;
Δ = b2-4ac
Δ = 6652-4·(-1)·(-9750)
Δ = 403225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{403225}=635$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(665)-635}{2*-1}=\frac{-1300}{-2}
=+650
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(665)+635}{2*-1}=\frac{-30}{-2}
=+15
$