912=(x+9)(x+2)4

Solution for 912=(x+9)(x+2)4 equation:

Simplifying
912 = (x + 9)(x + 2) * 4

Reorder the terms:
912 = (9 + x)(x + 2) * 4

Reorder the terms:
912 = (9 + x)(2 + x) * 4

Reorder the terms for easier multiplication:
912 = 4(9 + x)(2 + x)

Multiply (9 + x) * (2 + x)
912 = 4(9(2 + x) + x(2 + x))
912 = 4((2 * 9 + x * 9) + x(2 + x))
912 = 4((18 + 9x) + x(2 + x))
912 = 4(18 + 9x + (2 * x + x * x))
912 = 4(18 + 9x + (2x + x2))

Combine like terms: 9x + 2x = 11x
912 = 4(18 + 11x + x2)
912 = (18 * 4 + 11x * 4 + x2 * 4)
912 = (72 + 44x + 4x2)

Solving
912 = 72 + 44x + 4x2

Solving for variable 'x'.

Combine like terms: 912 + -72 = 840
840 + -44x + -4x2 = 72 + 44x + 4x2 + -72 + -44x + -4x2

Reorder the terms:
840 + -44x + -4x2 = 72 + -72 + 44x + -44x + 4x2 + -4x2

Combine like terms: 72 + -72 = 0
840 + -44x + -4x2 = 0 + 44x + -44x + 4x2 + -4x2
840 + -44x + -4x2 = 44x + -44x + 4x2 + -4x2

Combine like terms: 44x + -44x = 0
840 + -44x + -4x2 = 0 + 4x2 + -4x2
840 + -44x + -4x2 = 4x2 + -4x2

Combine like terms: 4x2 + -4x2 = 0
840 + -44x + -4x2 = 0

Factor out the Greatest Common Factor (GCF), '4'.
4(210 + -11x + -1x2) = 0

Factor a trinomial.
4((10 + -1x)(21 + x)) = 0

Ignore the factor 4.
Subproblem 1
Set the factor '(10 + -1x)' equal to zero and attempt to solve:

Simplifying
10 + -1x = 0

Solving
10 + -1x = 0

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

Add '-10' to each side of the equation.
10 + -10 + -1x = 0 + -10

Combine like terms: 10 + -10 = 0
0 + -1x = 0 + -10
-1x = 0 + -10

Combine like terms: 0 + -10 = -10
-1x = -10

Divide each side by '-1'.
x = 10

Simplifying
x = 10
Subproblem 2
Set the factor '(21 + x)' equal to zero and attempt to solve:

Simplifying
21 + x = 0

Solving
21 + x = 0

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

Add '-21' to each side of the equation.
21 + -21 + x = 0 + -21

Combine like terms: 21 + -21 = 0
0 + x = 0 + -21
x = 0 + -21

Combine like terms: 0 + -21 = -21
x = -21

Simplifying
x = -21
Solution
x = {10, -21}