40=(3+x)x

Solution for 40=(3+x)x equation:

Simplifying
40 = (3 + x) * x

Reorder the terms for easier multiplication:
40 = x(3 + x)
40 = (3 * x + x * x)
40 = (3x + x2)

Solving
40 = 3x + x2

Solving for variable 'x'.

Reorder the terms:
40 + -3x + -1x2 = 3x + -3x + x2 + -1x2

Combine like terms: 3x + -3x = 0
40 + -3x + -1x2 = 0 + x2 + -1x2
40 + -3x + -1x2 = x2 + -1x2

Combine like terms: x2 + -1x2 = 0
40 + -3x + -1x2 = 0

Factor a trinomial.
(5 + -1x)(8 + x) = 0

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

Simplifying
5 + -1x = 0

Solving
5 + -1x = 0

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

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

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

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

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

Simplifying
x = 5
Subproblem 2
Set the factor '(8 + x)' equal to zero and attempt to solve:

Simplifying
8 + x = 0

Solving
8 + x = 0

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

Add '-8' to each side of the equation.
8 + -8 + x = 0 + -8

Combine like terms: 8 + -8 = 0
0 + x = 0 + -8
x = 0 + -8

Combine like terms: 0 + -8 = -8
x = -8

Simplifying
x = -8
Solution
x = {5, -8}