(b+4)(b-9)=0

Solution for (b+4)(b-9)=0 equation:

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

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

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

Multiply (4 + b) * (-9 + b)
(4(-9 + b) + b(-9 + b)) = 0
((-9 * 4 + b * 4) + b(-9 + b)) = 0
((-36 + 4b) + b(-9 + b)) = 0
(-36 + 4b + (-9 * b + b * b)) = 0
(-36 + 4b + (-9b + b2)) = 0

Combine like terms: 4b + -9b = -5b
(-36 + -5b + b2) = 0

Solving
-36 + -5b + b2 = 0

Solving for variable 'b'.

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

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

Simplifying
-4 + -1b = 0

Solving
-4 + -1b = 0

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

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

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

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

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

Simplifying
b = -4
Subproblem 2
Set the factor '(9 + -1b)' equal to zero and attempt to solve:

Simplifying
9 + -1b = 0

Solving
9 + -1b = 0

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

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

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

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

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

Simplifying
b = 9
Solution
b = {-4, 9}