It's definitely ugly, but lines 2, 3 and 4 are equivalent to each other, so they are demonstrating what you are asking.

If I really wanted to do it this way for some reason, I'd say "let's assume that 2 is a solution (line 2). Equivalently, we have (line 3). Which is equivalent to 2=2, which is always right. Hence, our assumption was right."

I guess you would rather see "x^2 - x - 4/x = ... = 0" ?