x(-13-x)=42

Solution for x(-13-x)=42 equation:

Simplifying
x(-13 + -1x) = 42
(-13 * x + -1x * x) = 42
(-13x + -1x2) = 42

Solving
-13x + -1x2 = 42

Solving for variable 'x'.

Reorder the terms:
-42 + -13x + -1x2 = 42 + -42

Combine like terms: 42 + -42 = 0
-42 + -13x + -1x2 = 0

Factor out the Greatest Common Factor (GCF), '-1'.
-1(42 + 13x + x2) = 0

Factor a trinomial.
-1((7 + x)(6 + x)) = 0

Ignore the factor -1.
Subproblem 1
Set the factor '(7 + x)' equal to zero and attempt to solve:

Simplifying
7 + x = 0

Solving
7 + x = 0

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

Add '-7' to each side of the equation.
7 + -7 + x = 0 + -7

Combine like terms: 7 + -7 = 0
0 + x = 0 + -7
x = 0 + -7

Combine like terms: 0 + -7 = -7
x = -7

Simplifying
x = -7
Subproblem 2
Set the factor '(6 + x)' equal to zero and attempt to solve:

Simplifying
6 + x = 0

Solving
6 + x = 0

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

Add '-6' to each side of the equation.
6 + -6 + x = 0 + -6

Combine like terms: 6 + -6 = 0
0 + x = 0 + -6
x = 0 + -6

Combine like terms: 0 + -6 = -6
x = -6

Simplifying
x = -6
Solution
x = {-7, -6}