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# what is the X-Axis in the form y=mx+c

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1. I've used the X-axis in a question as y=1x+0, and got the right answer but with the wrong sign? Please can someone tell me if I have made a mistake with this equation? Thank you
2. The x axis is y=0.

y=x is the identity function represented by a diagonal line inclined at radians or from the axes.
3. (Original post by jazz_xox_)
I've used the X-axis in a question as y=1x+0, and got the right answer but with the wrong sign? Please can someone tell me if I have made a mistake with this equation? Thank you
At every single point on the x axis, y is equal to zero. So the equation for the x axis is not .
4. (Original post by Plagioclase)
At every single point on the x axis, y is equal to zero. So the equation for the x axis is not .
Thank you, I'm trying to use it in simultaneous equations with 4y=2x+23 but not sure how to cancel them by this method?

Edit: I think I've got it now by using y=0x+0, but my answer still has the wrong sign...
5. (Original post by jazz_xox_)
Thank you, I'm trying to use it in simultaneous equations with 4y=2x+23 but not sure how to cancel them by this method?

Edit: I think I've got it now by using y=0x+0, but my answer still has the wrong sign...
If your simultaneous equations are and , substitute into the first equation to get which you should then be able to solve.
6. (Original post by Plagioclase)
If your simultaneous equations are and , substitute into the first equation to get which you should then be able to solve.
Fab thank you! Do you know why I was getting the wrong sign by doing it with elimination? - I got my answer as 23/2 rather than -23/2
7. (Original post by jazz_xox_)
Fab thank you! Do you know why I was getting the wrong sign by doing it with elimination? - I got my answer as 23/2 rather than -23/2
Remember, you need to do the same thing to both sides of the equation. We want the x to be by itself so we subtract 23 from both sides to get .
8. (Original post by Plagioclase)
Remember, you need to do the same thing to both sides of the equation. We want the x to be by itself so we subtract 23 from both sides to get .
Thank you very much .

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