x(x*3.6)=20.77

Solution for x(x*3.6)=20.77 equation:

Simplifying
x(x * 3.6) = 20.77

Reorder the terms for easier multiplication:
x(3.6x) = 20.77

Remove parenthesis around (3.6x)
x * 3.6x = 20.77

Reorder the terms for easier multiplication:
3.6x * x = 20.77

Multiply x * x
3.6x2 = 20.77

Solving
3.6x2 = 20.77

Solving for variable 'x'.

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

Divide each side by '3.6'.
x2 = 5.769444444

Simplifying
x2 = 5.769444444

Take the square root of each side:
x = {-2.401966787, 2.401966787}