x^2+9x+21=1

Solution for x^2+9x+21=1 equation:

Simplifying
x2 + 9x + 21 = 1

Reorder the terms:
21 + 9x + x2 = 1

Solving
21 + 9x + x2 = 1

Solving for variable 'x'.

Reorder the terms:
21 + -1 + 9x + x2 = 1 + -1

Combine like terms: 21 + -1 = 20
20 + 9x + x2 = 1 + -1

Combine like terms: 1 + -1 = 0
20 + 9x + x2 = 0

Factor a trinomial.
(5 + x)(4 + x) = 0

Subproblem 1
Set the factor '(5 + x)' equal to zero and attempt to solve:

Simplifying
5 + x = 0

Solving
5 + x = 0

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

Add '-5' to each side of the equation.
5 + -5 + x = 0 + -5

Combine like terms: 5 + -5 = 0
0 + x = 0 + -5
x = 0 + -5

Combine like terms: 0 + -5 = -5
x = -5

Simplifying
x = -5
Subproblem 2
Set the factor '(4 + x)' equal to zero and attempt to solve:

Simplifying
4 + x = 0

Solving
4 + x = 0

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

Add '-4' to each side of the equation.
4 + -4 + x = 0 + -4

Combine like terms: 4 + -4 = 0
0 + x = 0 + -4
x = 0 + -4

Combine like terms: 0 + -4 = -4
x = -4

Simplifying
x = -4
Solution
x = {-5, -4}