36=r(r-5)

Solution for 36=r(r-5) equation:

Simplifying
36 = r(r + -5)

Reorder the terms:
36 = r(-5 + r)
36 = (-5 * r + r * r)
36 = (-5r + r2)

Solving
36 = -5r + r2

Solving for variable 'r'.

Reorder the terms:
36 + 5r + -1r2 = -5r + 5r + r2 + -1r2

Combine like terms: -5r + 5r = 0
36 + 5r + -1r2 = 0 + r2 + -1r2
36 + 5r + -1r2 = r2 + -1r2

Combine like terms: r2 + -1r2 = 0
36 + 5r + -1r2 = 0

Factor a trinomial.
(9 + -1r)(4 + r) = 0

Subproblem 1
Set the factor '(9 + -1r)' equal to zero and attempt to solve:

Simplifying
9 + -1r = 0

Solving
9 + -1r = 0

Move all terms containing r to the left, all other terms to the right.

Add '-9' to each side of the equation.
9 + -9 + -1r = 0 + -9

Combine like terms: 9 + -9 = 0
0 + -1r = 0 + -9
-1r = 0 + -9

Combine like terms: 0 + -9 = -9
-1r = -9

Divide each side by '-1'.
r = 9

Simplifying
r = 9
Subproblem 2
Set the factor '(4 + r)' equal to zero and attempt to solve:

Simplifying
4 + r = 0

Solving
4 + r = 0

Move all terms containing r to the left, all other terms to the right.

Add '-4' to each side of the equation.
4 + -4 + r = 0 + -4

Combine like terms: 4 + -4 = 0
0 + r = 0 + -4
r = 0 + -4

Combine like terms: 0 + -4 = -4
r = -4

Simplifying
r = -4
Solution
r = {9, -4}