(x-3)(x+18)=0

Solution for (x-3)(x+18)=0 equation:

Simplifying
(x + -3)(x + 18) = 0

Reorder the terms:
(-3 + x)(x + 18) = 0

Reorder the terms:
(-3 + x)(18 + x) = 0

Multiply (-3 + x) * (18 + x)
(-3(18 + x) + x(18 + x)) = 0
((18 * -3 + x * -3) + x(18 + x)) = 0
((-54 + -3x) + x(18 + x)) = 0
(-54 + -3x + (18 * x + x * x)) = 0
(-54 + -3x + (18x + x2)) = 0

Combine like terms: -3x + 18x = 15x
(-54 + 15x + x2) = 0

Solving
-54 + 15x + x2 = 0

Solving for variable 'x'.

Factor a trinomial.
(-18 + -1x)(3 + -1x) = 0

Subproblem 1
Set the factor '(-18 + -1x)' equal to zero and attempt to solve:

Simplifying
-18 + -1x = 0

Solving
-18 + -1x = 0

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

Add '18' to each side of the equation.
-18 + 18 + -1x = 0 + 18

Combine like terms: -18 + 18 = 0
0 + -1x = 0 + 18
-1x = 0 + 18

Combine like terms: 0 + 18 = 18
-1x = 18

Divide each side by '-1'.
x = -18

Simplifying
x = -18
Subproblem 2
Set the factor '(3 + -1x)' equal to zero and attempt to solve:

Simplifying
3 + -1x = 0

Solving
3 + -1x = 0

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

Add '-3' to each side of the equation.
3 + -3 + -1x = 0 + -3

Combine like terms: 3 + -3 = 0
0 + -1x = 0 + -3
-1x = 0 + -3

Combine like terms: 0 + -3 = -3
-1x = -3

Divide each side by '-1'.
x = 3

Simplifying
x = 3
Solution
x = {-18, 3}