(8-x)x=72

Solution for (8-x)x=72 equation:

Simplifying
(8 + -1x) * x = 72

Reorder the terms for easier multiplication:
x(8 + -1x) = 72
(8 * x + -1x * x) = 72
(8x + -1x2) = 72

Solving
8x + -1x2 = 72

Solving for variable 'x'.

Reorder the terms:
-72 + 8x + -1x2 = 72 + -72

Combine like terms: 72 + -72 = 0
-72 + 8x + -1x2 = 0

Begin completing the square.  Divide all terms by
-1 the coefficient of the squared term: 

Divide each side by '-1'.
72 + -8x + x2 = 0

Move the constant term to the right:

Add '-72' to each side of the equation.
72 + -8x + -72 + x2 = 0 + -72

Reorder the terms:
72 + -72 + -8x + x2 = 0 + -72

Combine like terms: 72 + -72 = 0
0 + -8x + x2 = 0 + -72
-8x + x2 = 0 + -72

Combine like terms: 0 + -72 = -72
-8x + x2 = -72

The x term is -8x.  Take half its coefficient (-4).
Square it (16) and add it to both sides.

Add '16' to each side of the equation.
-8x + 16 + x2 = -72 + 16

Reorder the terms:
16 + -8x + x2 = -72 + 16

Combine like terms: -72 + 16 = -56
16 + -8x + x2 = -56

Factor a perfect square on the left side:
(x + -4)(x + -4) = -56

Can't calculate square root of the right side.

The solution to this equation could not be determined.