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maths help

mariejuana

THANKS for your help guys

(edited 6 years ago)

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Reply 1

username3509752

Try multiplying both sides by e^(-x) and simplifying

Reply 2

mariejuana

Original post by Edgemaster

Try multiplying both sides by e^(-x) and simplifying

I've got to ye^-x=1+e^-2x
Now what

Reply 3

Notnek

Original post by mariejuana

y=e^x +e^-x
express in terms of y
No idea.
I've taken logs and all that stuff but I can't really find a way how to do it

This is possible but it's an odd question. Have you posted the question exactly as you see it? Is this working as part of a larger question?

Reply 4

mariejuana

Original post by Notnek

This is possible but it's an odd question. Have you posted the question exactly as you see it? Is this working as part of a larger question?

exact question=
given that y=e^x +e^-x
express X in terms of Y

Reply 5

username3509752

Original post by mariejuana

I've got to ye^-x=1+e^-2x
Now what

Honestly I'm not sure, I just remember seeing something similar and that multiplying by e^-x made it easier

Reply 6

Notnek

Original post by mariejuana

exact question=
given that y=e^x +e^-x
express X in terms of Y

Where did you get this question from?

If you let X = e^x then you have

y = X + 1/X

See if you can make X the subject of this.

Reply 7

mariejuana

Original post by Notnek

Where did you get this question from?

If you let X = e^x then you have

y = X + 1/X

See if you can make X the subject of this.

I'm currently doing as maths and this one of many questions from our half term homework assessment.

Reply 8

mariejuana

Original post by Notnek

Where did you get this question from?

If you let X = e^x then you have

y = X + 1/X

See if you can make X the subject of this.

Ican't xD

Reply 9

Notnek

Original post by mariejuana

Ican't xD

Please always post what you've tried.

y = X + 1/X

If instead of y you had e.g. 2 it would be

2 = X + 1/x

and you can rearrange this into a quadratic and solve. Try doing the same thing but for y instead of 2. Post your working if you get stuck.

By the way, you wouldn't see this question in a textbook or exam so I assume your teacher made it up? Are you doing A Level maths?

Reply 10

Notnek

Original post by Edgemaster

I haven't double checked this but I think it makes sense

Please don't post full solutions.

(edited 6 years ago)

Reply 11

username3509752

Original post by Notnek

Please don't post full solutions.

Sorry, I forgot

Reply 12

mariejuana

Original post by Notnek

Please don't post full solutions.

Had the answer on wolfraam anyway xD

Reply 13

Notnek

Original post by mariejuana

Had the answer on wolfraam anyway xD

Why did you ask for help then?

Reply 14

mariejuana

Original post by Notnek

Why did you ask for help then?

to see how to get to the answer

Reply 15

Notnek

Original post by mariejuana

to see how to get to the answer

Oh I thought you meant you had the full working on Wolfram Alpha.

Reply 16

mariejuana

Original post by Notnek

Oh I thought you meant you had the full working on Wolfram Alpha.

Could you possibly delete this thread now xD?

Reply 17

Notnek

Original post by mariejuana

Could you possibly delete this thread now xD?

I can't remove threads. Any reason why you want it deleted? Any question in the maths forum could be useful in the future for students who have the same question.

Reply 18

mariejuana

Original post by Notnek

I can't remove threads. Any reason why you want it deleted? Any question in the maths forum could be useful in the future for students who have the same question.

Don't want people to laugh at how stupid I am xD
all MY THREADS are me literally asking for help in maths

Reply 19

Notnek

Original post by mariejuana

Don't want people to laugh at how stupid I am xD
all MY THREADS are me literally asking for help in maths

But this was a tough question so no one is going to laugh at you. I bet the majority of A Level students couldn't do it.

For this reason it would be useful to keep it in the maths forum :smile: