81=(x-6)(3x)

Solution for 81=(x-6)(3x) equation:

Simplifying
81 = (x + -6)(3x)

Reorder the terms:
81 = (-6 + x)(3x)

Remove parenthesis around (3x)
81 = (-6 + x) * 3x

Reorder the terms for easier multiplication:
81 = 3x(-6 + x)
81 = (-6 * 3x + x * 3x)
81 = (-18x + 3x2)

Solving
81 = -18x + 3x2

Solving for variable 'x'.

Reorder the terms:
81 + 18x + -3x2 = -18x + 18x + 3x2 + -3x2

Combine like terms: -18x + 18x = 0
81 + 18x + -3x2 = 0 + 3x2 + -3x2
81 + 18x + -3x2 = 3x2 + -3x2

Combine like terms: 3x2 + -3x2 = 0
81 + 18x + -3x2 = 0

Factor out the Greatest Common Factor (GCF), '3'.
3(27 + 6x + -1x2) = 0

Factor a trinomial.
3((9 + -1x)(3 + x)) = 0

Ignore the factor 3.
Subproblem 1
Set the factor '(9 + -1x)' equal to zero and attempt to solve:

Simplifying
9 + -1x = 0

Solving
9 + -1x = 0

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

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

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

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

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

Simplifying
x = 9
Subproblem 2
Set the factor '(3 + x)' equal to zero and attempt to solve:

Simplifying
3 + x = 0

Solving
3 + x = 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 + x = 0 + -3

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

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

Simplifying
x = -3
Solution
x = {9, -3}