(x+1)(x+9)=0

Solution for (x+1)(x+9)=0 equation:

Simplifying
(x + 1)(x + 9) = 0

Reorder the terms:
(1 + x)(x + 9) = 0

Reorder the terms:
(1 + x)(9 + x) = 0

Multiply (1 + x) * (9 + x)
(1(9 + x) + x(9 + x)) = 0
((9 * 1 + x * 1) + x(9 + x)) = 0
((9 + 1x) + x(9 + x)) = 0
(9 + 1x + (9 * x + x * x)) = 0
(9 + 1x + (9x + x2)) = 0

Combine like terms: 1x + 9x = 10x
(9 + 10x + x2) = 0

Solving
9 + 10x + x2 = 0

Solving for variable 'x'.

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

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

Simplifying
9 + x = 0

Solving
9 + x = 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 + x = 0 + -9

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

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

Simplifying
x = -9
Subproblem 2
Set the factor '(1 + x)' equal to zero and attempt to solve:

Simplifying
1 + x = 0

Solving
1 + x = 0

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

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

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

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

Simplifying
x = -1
Solution
x = {-9, -1}