(k-9)(k+5)=

Solution for (k-9)(k+5)= equation:

Simplifying
(k + -9)(k + 5) = 0

Reorder the terms:
(-9 + k)(k + 5) = 0

Reorder the terms:
(-9 + k)(5 + k) = 0

Multiply (-9 + k) * (5 + k)
(-9(5 + k) + k(5 + k)) = 0
((5 * -9 + k * -9) + k(5 + k)) = 0
((-45 + -9k) + k(5 + k)) = 0
(-45 + -9k + (5 * k + k * k)) = 0
(-45 + -9k + (5k + k2)) = 0

Combine like terms: -9k + 5k = -4k
(-45 + -4k + k2) = 0

Solving
-45 + -4k + k2 = 0

Solving for variable 'k'.

Factor a trinomial.
(-5 + -1k)(9 + -1k) = 0

Subproblem 1
Set the factor '(-5 + -1k)' equal to zero and attempt to solve:

Simplifying
-5 + -1k = 0

Solving
-5 + -1k = 0

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

Add '5' to each side of the equation.
-5 + 5 + -1k = 0 + 5

Combine like terms: -5 + 5 = 0
0 + -1k = 0 + 5
-1k = 0 + 5

Combine like terms: 0 + 5 = 5
-1k = 5

Divide each side by '-1'.
k = -5

Simplifying
k = -5
Subproblem 2
Set the factor '(9 + -1k)' equal to zero and attempt to solve:

Simplifying
9 + -1k = 0

Solving
9 + -1k = 0

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

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

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

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

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

Simplifying
k = 9
Solution
k = {-5, 9}