r(r+11)-42=0

Solution for r(r+11)-42=0 equation:

Simplifying
r(r + 11) + -42 = 0

Reorder the terms:
r(11 + r) + -42 = 0
(11 * r + r * r) + -42 = 0
(11r + r2) + -42 = 0

Reorder the terms:
-42 + 11r + r2 = 0

Solving
-42 + 11r + r2 = 0

Solving for variable 'r'.

Factor a trinomial.
(-14 + -1r)(3 + -1r) = 0

Subproblem 1
Set the factor '(-14 + -1r)' equal to zero and attempt to solve:

Simplifying
-14 + -1r = 0

Solving
-14 + -1r = 0

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

Add '14' to each side of the equation.
-14 + 14 + -1r = 0 + 14

Combine like terms: -14 + 14 = 0
0 + -1r = 0 + 14
-1r = 0 + 14

Combine like terms: 0 + 14 = 14
-1r = 14

Divide each side by '-1'.
r = -14

Simplifying
r = -14
Subproblem 2
Set the factor '(3 + -1r)' equal to zero and attempt to solve:

Simplifying
3 + -1r = 0

Solving
3 + -1r = 0

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

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

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

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

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

Simplifying
r = 3
Solution
r = {-14, 3}