-x^2+x+72=0

Solution for -x^2+x+72=0 equation:

-x^2+x+72=0

We add all the numbers together, and all the variables

-1x^2+x+72=0

a = -1; b = 1; c = +72;
Δ = b2-4ac
Δ = 12-4·(-1)·72
Δ = 289
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{289}=17$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(1)-17}{2*-1}=\frac{-18}{-2}
=+9
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+17}{2*-1}=\frac{16}{-2}
=-8
$