If x and y are positive and sqrtx = y, which of the following must be equal 0?

A) x-y

B) x- sqrty

C) y-2x

D) y- x^2

E) y^2 -x

Square both sides:

From there, all you need to do is subtract!

You could also plug in! Say *x* = 49 and *y* = 7. Then it’s true that the square root of *x* equals *y*, and you can try each answer choice to see which equals 0. Only E will.