(t+9)(t-15)=0

Solution for (t+9)(t-15)=0 equation:

Simplifying
(t + 9)(t + -15) = 0

Reorder the terms:
(9 + t)(t + -15) = 0

Reorder the terms:
(9 + t)(-15 + t) = 0

Multiply (9 + t) * (-15 + t)
(9(-15 + t) + t(-15 + t)) = 0
((-15 * 9 + t * 9) + t(-15 + t)) = 0
((-135 + 9t) + t(-15 + t)) = 0
(-135 + 9t + (-15 * t + t * t)) = 0
(-135 + 9t + (-15t + t2)) = 0

Combine like terms: 9t + -15t = -6t
(-135 + -6t + t2) = 0

Solving
-135 + -6t + t2 = 0

Solving for variable 't'.

Factor a trinomial.
(-9 + -1t)(15 + -1t) = 0

Subproblem 1
Set the factor '(-9 + -1t)' equal to zero and attempt to solve:

Simplifying
-9 + -1t = 0

Solving
-9 + -1t = 0

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

Add '9' to each side of the equation.
-9 + 9 + -1t = 0 + 9

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

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

Divide each side by '-1'.
t = -9

Simplifying
t = -9
Subproblem 2
Set the factor '(15 + -1t)' equal to zero and attempt to solve:

Simplifying
15 + -1t = 0

Solving
15 + -1t = 0

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

Add '-15' to each side of the equation.
15 + -15 + -1t = 0 + -15

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

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

Divide each side by '-1'.
t = 15

Simplifying
t = 15
Solution
t = {-9, 15}