(a+9)(a-3)=

Solution for (a+9)(a-3)= equation:

Simplifying
(a + 9)(a + -3) = 0

Reorder the terms:
(9 + a)(a + -3) = 0

Reorder the terms:
(9 + a)(-3 + a) = 0

Multiply (9 + a) * (-3 + a)
(9(-3 + a) + a(-3 + a)) = 0
((-3 * 9 + a * 9) + a(-3 + a)) = 0
((-27 + 9a) + a(-3 + a)) = 0
(-27 + 9a + (-3 * a + a * a)) = 0
(-27 + 9a + (-3a + a2)) = 0

Combine like terms: 9a + -3a = 6a
(-27 + 6a + a2) = 0

Solving
-27 + 6a + a2 = 0

Solving for variable 'a'.

Factor a trinomial.
(-9 + -1a)(3 + -1a) = 0

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

Simplifying
-9 + -1a = 0

Solving
-9 + -1a = 0

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

Add '9' to each side of the equation.
-9 + 9 + -1a = 0 + 9

Combine like terms: -9 + 9 = 0
0 + -1a = 0 + 9
-1a = 0 + 9

Combine like terms: 0 + 9 = 9
-1a = 9

Divide each side by '-1'.
a = -9

Simplifying
a = -9
Subproblem 2
Set the factor '(3 + -1a)' equal to zero and attempt to solve:

Simplifying
3 + -1a = 0

Solving
3 + -1a = 0

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

Add '-3' to each side of the equation.
3 + -3 + -1a = 0 + -3

Combine like terms: 3 + -3 = 0
0 + -1a = 0 + -3
-1a = 0 + -3

Combine like terms: 0 + -3 = -3
-1a = -3

Divide each side by '-1'.
a = 3

Simplifying
a = 3
Solution
a = {-9, 3}