9(a+1)(a+2)=0

Solution for 9(a+1)(a+2)=0 equation:

Simplifying
9(a + 1)(a + 2) = 0

Reorder the terms:
9(1 + a)(a + 2) = 0

Reorder the terms:
9(1 + a)(2 + a) = 0

Multiply (1 + a) * (2 + a)
9(1(2 + a) + a(2 + a)) = 0
9((2 * 1 + a * 1) + a(2 + a)) = 0
9((2 + 1a) + a(2 + a)) = 0
9(2 + 1a + (2 * a + a * a)) = 0
9(2 + 1a + (2a + a2)) = 0

Combine like terms: 1a + 2a = 3a
9(2 + 3a + a2) = 0
(2 * 9 + 3a * 9 + a2 * 9) = 0
(18 + 27a + 9a2) = 0

Solving
18 + 27a + 9a2 = 0

Solving for variable 'a'.

Factor out the Greatest Common Factor (GCF), '9'.
9(2 + 3a + a2) = 0

Factor a trinomial.
9((2 + a)(1 + a)) = 0

Ignore the factor 9.
Subproblem 1
Set the factor '(2 + a)' equal to zero and attempt to solve:

Simplifying
2 + a = 0

Solving
2 + a = 0

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

Add '-2' to each side of the equation.
2 + -2 + a = 0 + -2

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

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

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

Simplifying
1 + a = 0

Solving
1 + a = 0

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

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

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

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

Simplifying
a = -1
Solution
a = {-2, -1}