# many to one or one to many maths problem

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Could someone please clarify if the mark scheme is wrong and it is many to one AND one to many... or just one to many?

thanks for any help I appreciate it

thanks for any help I appreciate it

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#2

The mark scheme is correct, an ellipse can never be many-to-one.

Many-to-one means that two x values are put in the function, and both will give the same result.

e.g

If you did and they would both give 0, the same y value, and only this value.

Your example does not work in the same way, because each x value corresponds to two y values, which means it must be one-to-many.

Many-to-one means that two x values are put in the function, and both will give the same result.

e.g

If you did and they would both give 0, the same y value, and only this value.

Your example does not work in the same way, because each x value corresponds to two y values, which means it must be one-to-many.

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#3

Interestingly, the "Cambridge International AS and A level mathematics" (2012 ISBN 978 1444 14644 8) describes a circle, which is very similar object to the one in this question, as many-many. And that is how I would describe it.

However, looking at at least one of the current syllabii - and this question - they only mention, one-one, one-many, and many-one. What's happened to "many-many"?

Is there something in how they've been defined that says if it's one-many then it can't be many-one as well.

Any teachers/educators in the know?

However, looking at at least one of the current syllabii - and this question - they only mention, one-one, one-many, and many-one. What's happened to "many-many"?

Is there something in how they've been defined that says if it's one-many then it can't be many-one as well.

Any teachers/educators in the know?

Last edited by ghostwalker; 4 weeks ago

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(Original post by

Interestingly, the "Cambridge International AS and A level mathematics" (2012 ISBN 978 1444 14644 8) describes a circle, which is very similar object to the one in this question, as many-many. And that is how I would describe it.

However, looking at at least one of the current syllabii - and this question - they only mention, one-one, one-many, and many-one. What's happened to "many-many"?

Is there something in how they've been defined that says if it's one-many then it can't be many-one as well.

Any teachers/educators in the know?

**ghostwalker**)Interestingly, the "Cambridge International AS and A level mathematics" (2012 ISBN 978 1444 14644 8) describes a circle, which is very similar object to the one in this question, as many-many. And that is how I would describe it.

However, looking at at least one of the current syllabii - and this question - they only mention, one-one, one-many, and many-one. What's happened to "many-many"?

Is there something in how they've been defined that says if it's one-many then it can't be many-one as well.

Any teachers/educators in the know?

*only*one y value. However, from the circle or elipses... we can't ever get a scenario where 2 x values = ONLY 1 y value because for every point of x within the range of the equation, there are always 2 y values... so its not 2 x = 1 y value, its more like, 2 x value = 2 y value... ?

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(Original post by

The mark scheme is correct, an ellipse can never be many-to-one.

Many-to-one means that two x values are put in the function, and both will give the same result.

e.g

If you did and they would both give 0, the same y value, and only this value.

Your example does not work in the same way, because each x value corresponds to two y values, which means it must be one-to-many.

**Smallwatch**)The mark scheme is correct, an ellipse can never be many-to-one.

Many-to-one means that two x values are put in the function, and both will give the same result.

e.g

If you did and they would both give 0, the same y value, and only this value.

Your example does not work in the same way, because each x value corresponds to two y values, which means it must be one-to-many.

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#6

(Original post by

That was my initial thought aswell... perhaps it's because the definition of many-to-one might be where two or more x values correspond to

**pondering-soul**)That was my initial thought aswell... perhaps it's because the definition of many-to-one might be where two or more x values correspond to

*only*one y value. However, from the circle or elipses... we can't ever get a scenario where 2 x values = ONLY 1 y value because for every point of x within the range of the equation, there are always 2 y values... so its not 2 x = 1 y value, its more like, 2 x value = 2 y value... ?The extremes of the ellipse along the x-axis are an example of where we have two x-values and only 1 y-value.

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(Original post by

For it to be many-one, we only require one y-value to have more than one corresponding x-value. In a Similar fashion for one-many.

The extremes of the ellipse along the x-axis are an example of where we have two x-values and only 1 y-value.

**ghostwalker**)For it to be many-one, we only require one y-value to have more than one corresponding x-value. In a Similar fashion for one-many.

The extremes of the ellipse along the x-axis are an example of where we have two x-values and only 1 y-value.

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