Let's expand the left side of the equation:

(х^2-2x)^2 - 3 = (x^2 - 2x)(x^2 - 2x) - 3
= x^4 - 4x^3 + 4x^2 - 3

Now let's simplify the right side of the equation:

2(x^2—2x) = 2x^2 - 4x

Therefore, we have:

x^4 - 4x^3 + 4x^2 - 3 = 2x^2 - 4x

Rearranging terms, we get:

x^4 - 4x^3 + 2x^2 + 4x - 3 = 0

So the equation is x^4 - 4x^3 + 2x^2 + 4x - 3 = 0.