(r+5)(r-18)=0

Solution for (r+5)(r-18)=0 equation:

Simplifying
(r + 5)(r + -18) = 0

Reorder the terms:
(5 + r)(r + -18) = 0

Reorder the terms:
(5 + r)(-18 + r) = 0

Multiply (5 + r) * (-18 + r)
(5(-18 + r) + r(-18 + r)) = 0
((-18 * 5 + r * 5) + r(-18 + r)) = 0
((-90 + 5r) + r(-18 + r)) = 0
(-90 + 5r + (-18 * r + r * r)) = 0
(-90 + 5r + (-18r + r2)) = 0

Combine like terms: 5r + -18r = -13r
(-90 + -13r + r2) = 0

Solving
-90 + -13r + r2 = 0

Solving for variable 'r'.

Factor a trinomial.
(-5 + -1r)(18 + -1r) = 0

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

Simplifying
-5 + -1r = 0

Solving
-5 + -1r = 0

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

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

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

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

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

Simplifying
r = -5
Subproblem 2
Set the factor '(18 + -1r)' equal to zero and attempt to solve:

Simplifying
18 + -1r = 0

Solving
18 + -1r = 0

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

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

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

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

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

Simplifying
r = 18
Solution
r = {-5, 18}