# Square root

• Aug 3rd 2006, 01:44 PM
bret80
Square root
Solve this equation when y=0

y=\sqrt{4-x^2}
• Aug 3rd 2006, 01:49 PM
topsquark
Quote:

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
• Aug 3rd 2006, 02:53 PM
ThePerfectHacker
Quote:

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.
• Aug 3rd 2006, 03:04 PM
topsquark
Quote:

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." :D

-Dan