A2 Functions: Question Help Needed!
Hey guys, today I came across a particularly tricky question in Maths class today and hoped that I could get a solution on here (teacher struggled to answer).
Here it is:
2. By drawing a sketch or otherwise, state whether each mapping is:
i) One-one, many-one, one-many, many-many.
ii) A function.
The mapping in paticular is:
g) y = 3-x for x≤2, 0 for x≥2
I answered that it was many-many (multiple y values for x=2, and multiple x values for y=0) and not a function (breaks in the middle).
This was wrong, with the correct answer being one-many, and not a function.
Why is this the case?
Any help would be appreciated
Here it is:
2. By drawing a sketch or otherwise, state whether each mapping is:
i) One-one, many-one, one-many, many-many.
ii) A function.
The mapping in paticular is:
g) y = 3-x for x≤2, 0 for x≥2
I answered that it was many-many (multiple y values for x=2, and multiple x values for y=0) and not a function (breaks in the middle).
This was wrong, with the correct answer being one-many, and not a function.
Why is this the case?
Any help would be appreciated
Original post by TheWingDingKing
Hey guys, today I came across a particularly tricky question in Maths class today and hoped that I could get a solution on here (teacher struggled to answer).
Here it is:
2. By drawing a sketch or otherwise, state whether each mapping is:
i) One-one, many-one, one-many, many-many.
ii) A function.
The mapping in paticular is:
g) y = 3-x for x≤2, 0 for x≥2
I answered that it was many-many (multiple y values for x=2, and multiple x values for y=0) and not a function (breaks in the middle).
This was wrong, with the correct answer being one-many, and not a function.
Why is this the case?
Any help would be appreciated
Here it is:
2. By drawing a sketch or otherwise, state whether each mapping is:
i) One-one, many-one, one-many, many-many.
ii) A function.
The mapping in paticular is:
g) y = 3-x for x≤2, 0 for x≥2
I answered that it was many-many (multiple y values for x=2, and multiple x values for y=0) and not a function (breaks in the middle).
This was wrong, with the correct answer being one-many, and not a function.
Why is this the case?
Any help would be appreciated
It's not many-to-many. That would mean there is some x value which provides two or more y values, and there is also some y value which is obtained from two or more x values.
The second part of that sentence is not found to be true for this example.
The first part, however, is indeed true for particularly x=2.
Hence, this is one-to-many. And it's not a function, because functions require you to have only one output every every possible input. Just because there is break does not automatically mean it's not a function.
(edited 4 years ago)
Wouldn't Y=0 be obtained from X=2,3,4.....?
Why doesn't that make it many-many?
Thanks for replying BTW
Why doesn't that make it many-many?
Thanks for replying BTW
Original post by TheWingDingKing
Wouldn't Y=0 be obtained from X=2,3,4.....?
Why doesn't that make it many-many?
Thanks for replying BTW
Why doesn't that make it many-many?
Thanks for replying BTW
You are quite correct, and I suspect that myself alongside with the author of this question have fell into the same pit when trying to answer it.
So indeed, is many-to-many relation but it's not a function for the same reason as I've said above.
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