1. The problem statement, all variables and given/known data sqrtY^2=sqrtX^2 Solving for Y we get: Y= X and Y= -X 2. Relevant equations 3. The attempt at a solution Since both sides of sqrtY^2=sqrtX^2 are equal I thought the equation would solve simply as Y= X. Turns out it has also the second part Y= -X. My questions are since both sides of the equation sqrtY^2= sqrtX^2 are EQUAL 1. why don't we just get Y=X or 2. why Y also doesn't take the negative sign just to keep the both sides of the orginal equation in balance? Thanks.