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November 08, 2025, 05:10:17 am

Author Topic: Need Help ASAP, SAC tomorrow  (Read 840 times)  Share 

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oliverk94

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Need Help ASAP, SAC tomorrow
« on: March 13, 2012, 07:52:51 pm »
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Hey guys. So I have a SAC tomorrow and I've done all the Practice SACs my teacher gave me but she didn't give us the answers, so I don't know whether my answers are right or not. Could you guys possibly give me the answers to these questions:

1) A curve is given by the rule

d) Will the inverse exist

e) Write the equation for the inverse

2) Is a function?

3) Does exist as a function?

d) Calculate the points at which f(x) intersects with

6)
a) Does exist as a function?
b) Restrict the domain of f(x) so that f-1(x) exists as a function.

- I don't seem to understand what f-1(x) means, is that the inverse of the graph? So for f(x)=x2, the f-1 (x) will be sqrt root x?

- I don't know how to restrict the domain properly. Do you restrict the for f(x) or for f-1(x)?

EDIT: sorry for bad latex I used an online latex convertor
« Last Edit: March 13, 2012, 07:54:31 pm by oliverk94 »

Phy124

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Re: Need Help ASAP, SAC tomorrow
« Reply #1 on: March 13, 2012, 08:59:54 pm »
+1
1) d) Yes as the function is one-to-one

e) For inverse, swap x and y, therefore;











2) Maybe I'm missing something but, yes? IIRC, a function may have to be to one-to-one so this may be incorrect, not sure.

3) Same as 2... yes?

d) Either solve the inverse to equal the original or solve either (the original or the inverse) to equal x (as they are symmetrical about the line y=x if they intersect it must be on this line)

6) a) No as is not a one-to-one function
b) You need to restrict the domain such that the function will be one-to-one. As the turning point is at 2, the maximal domain such that the function will be one-to-one will be either or

*Note the inverse function will exist if for the domain the second value is < 2 and for the domain the left value is > 2 (those two are just the largest possible)

- Yes refers to the inversion function of . The inverse function of will only exist if the domain is restricted to make it one-to-one. For example if the domain of was then the inverse function would be . But if the domain of was the the inverse function would be as range = domain.

- You restrict the domain of such that is a one-to-one function so that will exist
« Last Edit: March 15, 2012, 11:07:22 am by ~My♥Little♥Pony~ »
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oliverk94

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Re: Need Help ASAP, SAC tomorrow
« Reply #2 on: March 13, 2012, 09:06:06 pm »
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Legend! Thanks man.


« Last Edit: March 13, 2012, 09:15:12 pm by oliverk94 »

Phy124

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Re: Need Help ASAP, SAC tomorrow
« Reply #3 on: March 13, 2012, 09:13:09 pm »
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Legend! Thanks man.

So for example to make if you were to make f-1(x) exist for f(x)=x2 Would you write it as this:
f: [0, inf) -> R, f(x)=x2?

This is what I get confused about.



No worries, I hope I interpreted 2) and 3) correctly, because they are pretty interesting things to ask , so it's really making me question myself  ::) Hopefully they're right!  ;)

Also, for the latex, you might benefit from using this. It's pretty easy to use and has buttons to set up formulas and equations, then you can just copy the code across and put it in
Code: [Select]
[tex][/tex] or copy the image file which is created across.

Yes, that is correct, as you have restricted the domain such that it is now a one-to-one function. That would be a possible answer if the question asked you two restrict the function to it's maximal domain such that still existed. As if the domain started at < 0 and went to infinity it would not be one-to-one.
« Last Edit: March 13, 2012, 09:16:25 pm by ~My♥Little♥Pony~ »
2011
Mathematical Methods | Physics | Chemistry | English | Business Management

2012-2017
Bachelor of Science in Applied Mathematics and Bachelor of Civil Engineering (Honours) @ Monash University

Current
Transport Modeller @ Arup

oliverk94

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Re: Need Help ASAP, SAC tomorrow
« Reply #4 on: March 13, 2012, 09:16:01 pm »
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Thanks.

Sorry If I keep editing my posts haha!
« Last Edit: March 13, 2012, 09:18:31 pm by oliverk94 »