(x+9)(x-1)=-21

Solution for (x+9)(x-1)=-21 equation:

Simplifying
(x + 9)(x + -1) = -21

Reorder the terms:
(9 + x)(x + -1) = -21

Reorder the terms:
(9 + x)(-1 + x) = -21

Multiply (9 + x) * (-1 + x)
(9(-1 + x) + x(-1 + x)) = -21
((-1 * 9 + x * 9) + x(-1 + x)) = -21
((-9 + 9x) + x(-1 + x)) = -21
(-9 + 9x + (-1 * x + x * x)) = -21
(-9 + 9x + (-1x + x2)) = -21

Combine like terms: 9x + -1x = 8x
(-9 + 8x + x2) = -21

Solving
-9 + 8x + x2 = -21

Solving for variable 'x'.

Reorder the terms:
-9 + 21 + 8x + x2 = -21 + 21

Combine like terms: -9 + 21 = 12
12 + 8x + x2 = -21 + 21

Combine like terms: -21 + 21 = 0
12 + 8x + x2 = 0

Factor a trinomial.
(6 + x)(2 + x) = 0

Subproblem 1
Set the factor '(6 + x)' equal to zero and attempt to solve:

Simplifying
6 + x = 0

Solving
6 + x = 0

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

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

Combine like terms: 6 + -6 = 0
0 + x = 0 + -6
x = 0 + -6

Combine like terms: 0 + -6 = -6
x = -6

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

Simplifying
2 + x = 0

Solving
2 + x = 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 + x = 0 + -2

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

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

Simplifying
x = -2
Solution
x = {-6, -2}