9r^2-36r-45=0

Solution for 9r^2-36r-45=0 equation:

Simplifying
9r2 + -36r + -45 = 0

Reorder the terms:
-45 + -36r + 9r2 = 0

Solving
-45 + -36r + 9r2 = 0

Solving for variable 'r'.

Factor out the Greatest Common Factor (GCF), '9'.
9(-5 + -4r + r2) = 0

Factor a trinomial.
9((-1 + -1r)(5 + -1r)) = 0

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

Simplifying
-1 + -1r = 0

Solving
-1 + -1r = 0

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

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

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

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

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

Simplifying
r = -1
Subproblem 2
Set the factor '(5 + -1r)' equal to zero and attempt to solve:

Simplifying
5 + -1r = 0

Solving
5 + -1r = 0

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

Add '-5' to each side of the equation.
5 + -5 + -1r = 0 + -5

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

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

Divide each side by '-1'.
r = 5

Simplifying
r = 5
Solution
r = {-1, 5}