1. ## Square root

Solve this equation when y=0

y=\sqrt{4-x^2}

2. Originally Posted by bret80
Solve this equation when y=0

y=\sqrt{4-x^2}
First of all, to do LaTeX, you need to put your expression between [ math ] and [ /math ] . (Without the spaces!)

$0 = \sqrt{4-x^2}$. Square both sides:

$0 = 4 - x^2$

$x^2 = 4$

$x = \pm 2$

Whenever you square both sides of an equation ALWAYS check to make sure that your solution set satisfies your original equation as squaring occasionally adds extra solutions. In this case, both solutions work.

-Dan

3. Originally Posted by topsquark
Whenever you square both sides of an equation ALWAYS check to make sure that your solution set satisfies your original equation as squaring occasionally adds extra solutions.
Not neccesarily. If all of your steps are equivalent to each other (if and only if; you might have seen me do that a number of times) then no check is required.

4. Originally Posted by ThePerfectHacker
Not neccesarily. If all of your steps are equivalent to each other (if and only if; you might have seen me do that a number of times) then no check is required.
Well, it's a good idea for us "lesser mortals" anyway. We can't ALL be "perfect."

-Dan