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**HallsofIvy** Okay, [b]why[b] did you do that? What happened to the point (1, 0)? What you give (until your last line) is the distance from $\displaystyle (x, \sqrt{x})$ to (0, 0). But your last line is wrong- $\displaystyle x^2+ x= x(x+1)$, not $\displaystyle \sqrt{x^2+ x}$. For that you still need the square root: $\displaystyle \sqrt{x^2+ x}= \sqrt{x(x+1)}$.

But as I said, that would give the distance to (0, 0), not (1, 0).

Start with d= \sqrt{(x- 1)^2+ (y- 0)^2}= \sqrt{(x- 1)^2+ y^2}[/tex] and then replace $\displaystyle y^2$ with x.