6r^2-15r-99=0

Solution for 6r^2-15r-99=0 equation:

Simplifying
6r2 + -15r + -99 = 0

Reorder the terms:
-99 + -15r + 6r2 = 0

Solving
-99 + -15r + 6r2 = 0

Solving for variable 'r'.

Factor out the Greatest Common Factor (GCF), '3'.
3(-33 + -5r + 2r2) = 0

Factor a trinomial.
3((-3 + -1r)(11 + -2r)) = 0

Ignore the factor 3.
Subproblem 1
Set the factor '(-3 + -1r)' equal to zero and attempt to solve:

Simplifying
-3 + -1r = 0

Solving
-3 + -1r = 0

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

Add '3' to each side of the equation.
-3 + 3 + -1r = 0 + 3

Combine like terms: -3 + 3 = 0
0 + -1r = 0 + 3
-1r = 0 + 3

Combine like terms: 0 + 3 = 3
-1r = 3

Divide each side by '-1'.
r = -3

Simplifying
r = -3
Subproblem 2
Set the factor '(11 + -2r)' equal to zero and attempt to solve:

Simplifying
11 + -2r = 0

Solving
11 + -2r = 0

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

Add '-11' to each side of the equation.
11 + -11 + -2r = 0 + -11

Combine like terms: 11 + -11 = 0
0 + -2r = 0 + -11
-2r = 0 + -11

Combine like terms: 0 + -11 = -11
-2r = -11

Divide each side by '-2'.
r = 5.5

Simplifying
r = 5.5
Solution
r = {-3, 5.5}