(11+x)(x)=390

Solution for (11+x)(x)=390 equation:

Simplifying
(11 + x)(x) = 390

Reorder the terms for easier multiplication:
x(11 + x) = 390
(11 * x + x * x) = 390
(11x + x2) = 390

Solving
11x + x2 = 390

Solving for variable 'x'.

Reorder the terms:
-390 + 11x + x2 = 390 + -390

Combine like terms: 390 + -390 = 0
-390 + 11x + x2 = 0

Factor a trinomial.
(-26 + -1x)(15 + -1x) = 0

Subproblem 1
Set the factor '(-26 + -1x)' equal to zero and attempt to solve:

Simplifying
-26 + -1x = 0

Solving
-26 + -1x = 0

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

Add '26' to each side of the equation.
-26 + 26 + -1x = 0 + 26

Combine like terms: -26 + 26 = 0
0 + -1x = 0 + 26
-1x = 0 + 26

Combine like terms: 0 + 26 = 26
-1x = 26

Divide each side by '-1'.
x = -26

Simplifying
x = -26
Subproblem 2
Set the factor '(15 + -1x)' equal to zero and attempt to solve:

Simplifying
15 + -1x = 0

Solving
15 + -1x = 0

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

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

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

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

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

Simplifying
x = 15
Solution
x = {-26, 15}