If x is the difficulty, the phrase either means “twice the difficulty, squared”: (2x)^2 or 4x^2. Or “the difficulty squared and squared again”: (x^2)^2 or x^4.

If x is the difficulty, the phrase either means “twice the difficulty, squared”: (2x)^2 or 4x^2. Or “the difficulty squared and squared again”: (x^2)^2 or x^4. The GP is asking why x == 2 in the second example rather than just “the difficulty”. English interpretation doesn’t explain that.