128=x(2x)

Solution for 128=x(2x) equation:

Simplifying
128 = x(2x)

Remove parenthesis around (2x)
128 = x * 2x

Reorder the terms for easier multiplication:
128 = 2x * x

Multiply x * x
128 = 2x2

Solving
128 = 2x2

Solving for variable 'x'.

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

Add '-2x2' to each side of the equation.
128 + -2x2 = 2x2 + -2x2

Combine like terms: 2x2 + -2x2 = 0
128 + -2x2 = 0

Add '-128' to each side of the equation.
128 + -128 + -2x2 = 0 + -128

Combine like terms: 128 + -128 = 0
0 + -2x2 = 0 + -128
-2x2 = 0 + -128

Combine like terms: 0 + -128 = -128
-2x2 = -128

Divide each side by '-2'.
x2 = 64

Simplifying
x2 = 64

Take the square root of each side:
x = {-8, 8}