# x/x^2 - 9 re-arranged as a quadratic equation

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#1
I have the equation: I am asked to show how the equation can be rearranged as a quadratic equation in x provided y not equal 0

OK so I realise x/x^2 - 9 is a rational function. It could be expressed as: So to express as an equation I could do like this: Is that all that is required?

Or do I have to do more? If so any hints would be much appreciated.
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5 years ago
#2
(Original post by acomber)
I have the expression: I am asked to show how the equation can be rearranged as a quadratic equation in x provided y not equal 0
THis make no sense

You cannot rearrange an expression to make an equation

There is no y in your question
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#3
Sorry I made a mistake - should be y = . I will edit question.
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5 years ago
#4
(Original post by acomber)
Sorry I made a mistake - should be y = . I will edit question.
So now you have put y=0 in spite of the fact that the questions said y is not 0

The question still does not really make sense
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5 years ago
#5
(Original post by acomber)
I have the equation: I am asked to show how the equation can be rearranged as a quadratic equation in x provided y not equal 0

OK so I realise x/x^2 - 9 is a rational function. It could be expressed as: So to express as an equation I could do like this: Is that all that is required?

Or do I have to do more? If so any hints would be much appreciated.
No idea why you're setting that equal to 0.

To rearrange your original equation as a quadratic equation in x, simply multiply both sides by the denominator then rearrange terms so it looks like a standard quadratic equation. There's no need to be factorizing anything at this stage.
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#6
I am confused still.

You mean like this:

y(x^2 - 9) = x

x^2y - 9y = x

Then what?

(Original post by davros)
No idea why you're setting that equal to 0.

To rearrange your original equation as a quadratic equation in x, simply multiply both sides by the denominator then rearrange terms so it looks like a standard quadratic equation. There's no need to be factorizing anything at this stage.
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5 years ago
#7
move the x over to the other side, so that its like:

ax^2+bx+c=0
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#8
You mean like this? (Original post by Hasufel)
move the x over to the other side, so that its like:

ax^2+bx+c=0
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5 years ago
#9
Yes, although it would be more usual to write this as to make it explicit that it is a quadratic equation in the variable x.
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