-x2+22x-72=0

Solution for -x2+22x-72=0 equation:

-x2+22x-72=0

We add all the numbers together, and all the variables

-1x^2+22x-72=0

a = -1; b = 22; c = -72;
Δ = b2-4ac
Δ = 222-4·(-1)·(-72)
Δ = 196
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{196}=14$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(22)-14}{2*-1}=\frac{-36}{-2}
=+18
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(22)+14}{2*-1}=\frac{-8}{-2}
=+4
$