- #1

- 24

- 0

b.) cos (ln x) on (0, e^pi)

c.) e^(x^2) on (-1,2)

I am stuck and have no clue. I have only been able to get through basic questions like this, how do you complete these?

Thanks for any help.

- Thread starter adelaide87
- Start date

- #1

- 24

- 0

b.) cos (ln x) on (0, e^pi)

c.) e^(x^2) on (-1,2)

I am stuck and have no clue. I have only been able to get through basic questions like this, how do you complete these?

Thanks for any help.

- #2

lanedance

Homework Helper

- 3,304

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welcome to pf by the way ;)

it generally works here by you having an attempt & and people will help steer you through the problem - though you still do the work

- #3

Dick

Science Advisor

Homework Helper

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- #4

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Do you need to actually rearrange to see if its invertible or is there a other method? (aka just by looking?)

a) sechx is not 1-1 (can tell from plotting it)

b) Not sure

c) not 1-1 (from graph)

- #5

Dick

Science Advisor

Homework Helper

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I'm not much on calculators so I can't answer the first question, but if you plotted sech(x) then, yes, it's not invertible, BUT you are only looking at the (0,infinity) part. Do you want to rethink that opinion? To prove a function is NOT invertible you only need to find two values of x, say x1 and x2 such that f(x1)=f(x2).

Do you need to actually rearrange to see if its invertible or is there a other method? (aka just by looking?)

a) sechx is not 1-1 (can tell from plotting it)

b) Not sure

c) not 1-1 (from graph)

- #6

Char. Limit

Gold Member

- 1,204

- 14

Also, cos(ln(x)) is easy to do on a TI calculator. Just make sure you know your bounds.

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