(x+4)(x)=320

Solution for (x+4)(x)=320 equation:

Simplifying
(x + 4)(x) = 320

Reorder the terms:
(4 + x)(x) = 320

Reorder the terms for easier multiplication:
x(4 + x) = 320
(4 * x + x * x) = 320
(4x + x2) = 320

Solving
4x + x2 = 320

Solving for variable 'x'.

Reorder the terms:
-320 + 4x + x2 = 320 + -320

Combine like terms: 320 + -320 = 0
-320 + 4x + x2 = 0

Factor a trinomial.
(-20 + -1x)(16 + -1x) = 0

Subproblem 1
Set the factor '(-20 + -1x)' equal to zero and attempt to solve:

Simplifying
-20 + -1x = 0

Solving
-20 + -1x = 0

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

Add '20' to each side of the equation.
-20 + 20 + -1x = 0 + 20

Combine like terms: -20 + 20 = 0
0 + -1x = 0 + 20
-1x = 0 + 20

Combine like terms: 0 + 20 = 20
-1x = 20

Divide each side by '-1'.
x = -20

Simplifying
x = -20
Subproblem 2
Set the factor '(16 + -1x)' equal to zero and attempt to solve:

Simplifying
16 + -1x = 0

Solving
16 + -1x = 0

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

Add '-16' to each side of the equation.
16 + -16 + -1x = 0 + -16

Combine like terms: 16 + -16 = 0
0 + -1x = 0 + -16
-1x = 0 + -16

Combine like terms: 0 + -16 = -16
-1x = -16

Divide each side by '-1'.
x = 16

Simplifying
x = 16
Solution
x = {-20, 16}