(c+6)(c-15)=0

Solution for (c+6)(c-15)=0 equation:

Simplifying
(c + 6)(c + -15) = 0

Reorder the terms:
(6 + c)(c + -15) = 0

Reorder the terms:
(6 + c)(-15 + c) = 0

Multiply (6 + c) * (-15 + c)
(6(-15 + c) + c(-15 + c)) = 0
((-15 * 6 + c * 6) + c(-15 + c)) = 0
((-90 + 6c) + c(-15 + c)) = 0
(-90 + 6c + (-15 * c + c * c)) = 0
(-90 + 6c + (-15c + c2)) = 0

Combine like terms: 6c + -15c = -9c
(-90 + -9c + c2) = 0

Solving
-90 + -9c + c2 = 0

Solving for variable 'c'.

Factor a trinomial.
(-6 + -1c)(15 + -1c) = 0

Subproblem 1
Set the factor '(-6 + -1c)' equal to zero and attempt to solve:

Simplifying
-6 + -1c = 0

Solving
-6 + -1c = 0

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

Add '6' to each side of the equation.
-6 + 6 + -1c = 0 + 6

Combine like terms: -6 + 6 = 0
0 + -1c = 0 + 6
-1c = 0 + 6

Combine like terms: 0 + 6 = 6
-1c = 6

Divide each side by '-1'.
c = -6

Simplifying
c = -6
Subproblem 2
Set the factor '(15 + -1c)' equal to zero and attempt to solve:

Simplifying
15 + -1c = 0

Solving
15 + -1c = 0

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

Add '-15' to each side of the equation.
15 + -15 + -1c = 0 + -15

Combine like terms: 15 + -15 = 0
0 + -1c = 0 + -15
-1c = 0 + -15

Combine like terms: 0 + -15 = -15
-1c = -15

Divide each side by '-1'.
c = 15

Simplifying
c = 15
Solution
c = {-6, 15}