4536-r^2-9r=0

Solution for 4536-r^2-9r=0 equation:

4536-r^2-9r=0

We add all the numbers together, and all the variables

-1r^2-9r+4536=0

a = -1; b = -9; c = +4536;
Δ = b2-4ac
Δ = -92-4·(-1)·4536
Δ = 18225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{18225}=135$
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-9)-135}{2*-1}=\frac{-126}{-2}
=+63
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-9)+135}{2*-1}=\frac{144}{-2}
=-72
$