# Thread: Simple square rooting confusion

1. ## Simple square rooting confusion

Is y^2 = 4 - x^2 the same as:

y= 2 - x

OR

y= (4 - x^2)/y

Thank you!

2. y^2=4-x^2
y=(4-x^2)^0.5 i suppose that it is equal to you second equation also.
you must consider the right hand side of you equation in brakets when taking roots/squares. hope that helps
(you must take the posotive and negative of (4-x^2)^0.5)

3. Originally Posted by RB89
Is y^2 = 4 - x^2 the same as:

y= 2 - x

OR

y= (4 - x^2)/y

Thank you!
Hi RB89,

If you're wanting to solve for y, you will need to take the square root of both sides of the equation.

$y^2=4-x^2$

$y=\sqrt{4-x^2}$

And that's about it.

Now, if you had something like: $y^2=4x^2$, you could get to $y=2x$ because the right side of the equation was a perfect square. That wasn't the case in your example.

4. Originally Posted by RB89
Is y^2 = 4 - x^2 the same as:

y= 2 - x

OR

y= (4 - x^2)/y

Thank you!

$y^2=4-x^2$ is NOT the same as y=2-x

but it is the same as $y=\frac{4-x^2}{y}$ , when you work it out , you should see that they are the same .