4r^2-21r=18

Solution for 4r^2-21r=18 equation:

Simplifying
4r2 + -21r = 18

Reorder the terms:
-21r + 4r2 = 18

Solving
-21r + 4r2 = 18

Solving for variable 'r'.

Reorder the terms:
-18 + -21r + 4r2 = 18 + -18

Combine like terms: 18 + -18 = 0
-18 + -21r + 4r2 = 0

Factor a trinomial.
(-3 + -4r)(6 + -1r) = 0

Subproblem 1
Set the factor '(-3 + -4r)' equal to zero and attempt to solve:

Simplifying
-3 + -4r = 0

Solving
-3 + -4r = 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 + -4r = 0 + 3

Combine like terms: -3 + 3 = 0
0 + -4r = 0 + 3
-4r = 0 + 3

Combine like terms: 0 + 3 = 3
-4r = 3

Divide each side by '-4'.
r = -0.75

Simplifying
r = -0.75
Subproblem 2
Set the factor '(6 + -1r)' equal to zero and attempt to solve:

Simplifying
6 + -1r = 0

Solving
6 + -1r = 0

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

Add '-6' to each side of the equation.
6 + -6 + -1r = 0 + -6

Combine like terms: 6 + -6 = 0
0 + -1r = 0 + -6
-1r = 0 + -6

Combine like terms: 0 + -6 = -6
-1r = -6

Divide each side by '-1'.
r = 6

Simplifying
r = 6
Solution
r = {-0.75, 6}