80=x(5x)

Solution for 80=x(5x) equation:

Simplifying
80 = x(5x)

Remove parenthesis around (5x)
80 = x * 5x

Reorder the terms for easier multiplication:
80 = 5x * x

Multiply x * x
80 = 5x2

Solving
80 = 5x2

Solving for variable 'x'.

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

Add '-5x2' to each side of the equation.
80 + -5x2 = 5x2 + -5x2

Combine like terms: 5x2 + -5x2 = 0
80 + -5x2 = 0

Add '-80' to each side of the equation.
80 + -80 + -5x2 = 0 + -80

Combine like terms: 80 + -80 = 0
0 + -5x2 = 0 + -80
-5x2 = 0 + -80

Combine like terms: 0 + -80 = -80
-5x2 = -80

Divide each side by '-5'.
x2 = 16

Simplifying
x2 = 16

Take the square root of each side:
x = {-4, 4}