# Thread: How to find X

1. ## How to find X

Hello,
This is a lame questions, but my brain is fried and having trouble getting this

I have y=x^3 with y = 8

How do I find X
do I multiply both sides by 3 root then I have
3root of 8=x??

Thanks

2. ## Re: How to find X

You can do it like this:
$\displaystyle y=x^3$
$\displaystyle \Leftrightarrow \sqrt[3]{y}=\sqrt[3]{x^3}$
...

3. ## Re: How to find X

So I have 8=y^3.
So I raise both sides to 1/3 to cancel out the 3 on the x side.

so it's 8^1/3=x??
Do I have this correct?? from what I just read

4. ## Re: How to find X

I take the 3th root of each side, yes indeed take the 3th root of 8, which is? ...

5. ## Re: How to find X

I changed the 840am response. Check that one

6. ## Re: How to find X

so it's 8^1/3=x??
Do I have this correct?? from what I just read
This is correct, so $\displaystyle x=...$?

7. ## Re: How to find X

X=2.
THANKS ALL FOR YOUR HELP. I got this understanding now.

8. ## Re: How to find X

I changed the 840am response. Check that one
Just a note: most people on MHF have time set to their local time zone. This is an international forum, and we probably have about every time zone represented. Your "8:40" response reads as "12:40" on my computer. It's better to refer to post #, which is in the upper right corner of all posts.

9. ## Re: How to find X

Probably the best way to solve $\displaystyle x^3= 8$ is to recognize that $\displaystyle 8= 2^3$. So the equation is $\displaystyle x^3= 2^3$ and so x= 2.

10. ## Re: How to find X

Hello,
This is a lame questions, but my brain is fried and having trouble getting this

I have y=x^3 with y = 8

How do I find X
do I multiply both sides by 3 root then I have
3root of 8=x??

Thanks
Do you need to find the real cube root of 8, or do you need to find all three third roots of 8?