3x(x+1)=18

Solution for 3x(x+1)=18 equation:

Simplifying
3x(x + 1) = 18

Reorder the terms:
3x(1 + x) = 18
(1 * 3x + x * 3x) = 18
(3x + 3x2) = 18

Solving
3x + 3x2 = 18

Solving for variable 'x'.

Reorder the terms:
-18 + 3x + 3x2 = 18 + -18

Combine like terms: 18 + -18 = 0
-18 + 3x + 3x2 = 0

Factor out the Greatest Common Factor (GCF), '3'.
3(-6 + x + x2) = 0

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

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

Simplifying
-3 + -1x = 0

Solving
-3 + -1x = 0

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

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

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

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

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

Simplifying
x = -3
Subproblem 2
Set the factor '(2 + -1x)' equal to zero and attempt to solve:

Simplifying
2 + -1x = 0

Solving
2 + -1x = 0

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

Add '-2' to each side of the equation.
2 + -2 + -1x = 0 + -2

Combine like terms: 2 + -2 = 0
0 + -1x = 0 + -2
-1x = 0 + -2

Combine like terms: 0 + -2 = -2
-1x = -2

Divide each side by '-1'.
x = 2

Simplifying
x = 2
Solution
x = {-3, 2}