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plot x = 9 - y^2 with x as the horizontal axis

plot x = 9 - y^2 with x as the horizontal axis

Postby andieje » Sat Feb 13, 2010 6:47 pm
Hi

I'm trying to plot the function x = 9 - y^2 with x as the horizontal axis by typing "plot x = 9 - y^2" but it automatically puts x as the vertical and y as the horizontal axis. Do i have to re-write the function with y as the subject? Presumably there is a command to get wolfram alpha to rewrite this for me with y as the subject. Hopefully there is a command i can add to force WA to keep x as the horizontal axis

thanks
andieje
 
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Re: plot x = 9 - y^2 with x as the horizontal axis

Postby briangilbert » Tue Feb 16, 2010 8:37 am
Plot x = 9 - y^2 for y
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Re: plot x = 9 - y^2 with x as the horizontal axis

Postby andieje » Thu Feb 18, 2010 11:58 am
many thanks
andieje
 
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Re: plot x = 9 - y^2 with x as the horizontal axis

Postby andieje » Fri Feb 19, 2010 11:03 pm
Hi

Are you still there? I just assumed that would work but it didn't. It still plotted y as the horizontal axis instead of keeping x as the horizontal axis

thanks
andieje
 
Posts: 7
Joined: Sat Feb 13, 2010 6:43 pm

Re: plot x = 9 - y^2 with x as the horizontal axis

Postby briangilbert » Sat Feb 20, 2010 10:21 am
andieje wrote:Hi

Are you still there? I just assumed that would work but it didn't. It still plotted y as the horizontal axis instead of keeping x as the horizontal axis

thanks


Sorry about that. I am only fishing.
How about solving your equation for y, using Solve x=9-y^2
Giving plus or minus Sqare root (9-x)
Click on the answer to get the plain text.
Copy and paste the plaintext answer into a new input line.
Put 'Plot Y=' in front and remove the plus/minus sign.
giving your input as
Plot y = sqrt(9-x)
That gives an interesting result but is it what you are after?
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Re: plot x = 9 - y^2 with x as the horizontal axis

Postby andieje » Mon Feb 22, 2010 9:05 pm
Hi

That doesn't really work because in the plot x = 9-y^2 you get the points (0,3) and (0,-3)

If you plot y = (9-x)^1/2 then you only get (0,3)

thanks
andieje
 
Posts: 7
Joined: Sat Feb 13, 2010 6:43 pm

Re: plot x = 9 - y^2 with x as the horizontal axis

Postby briangilbert » Tue Feb 23, 2010 7:33 am
You seem to be satisfied with the original graph except that you want the x and the y axes interchanged.

Input the original graph into a picture editing program such as MS Paint. Rotate the image 90 degrees clockwise, and then flip it top to bottom.
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