(a+4)(a-9)=

Solution for (a+4)(a-9)= equation:

Simplifying
(a + 4)(a + -9) = 0

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

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

Multiply (4 + a) * (-9 + a)
(4(-9 + a) + a(-9 + a)) = 0
((-9 * 4 + a * 4) + a(-9 + a)) = 0
((-36 + 4a) + a(-9 + a)) = 0
(-36 + 4a + (-9 * a + a * a)) = 0
(-36 + 4a + (-9a + a2)) = 0

Combine like terms: 4a + -9a = -5a
(-36 + -5a + a2) = 0

Solving
-36 + -5a + a2 = 0

Solving for variable 'a'.

Factor a trinomial.
(-4 + -1a)(9 + -1a) = 0

Subproblem 1
Set the factor '(-4 + -1a)' equal to zero and attempt to solve:

Simplifying
-4 + -1a = 0

Solving
-4 + -1a = 0

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

Add '4' to each side of the equation.
-4 + 4 + -1a = 0 + 4

Combine like terms: -4 + 4 = 0
0 + -1a = 0 + 4
-1a = 0 + 4

Combine like terms: 0 + 4 = 4
-1a = 4

Divide each side by '-1'.
a = -4

Simplifying
a = -4
Subproblem 2
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
Solution
a = {-4, 9}