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Hello All, New Person Here


bloodhound

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Anyway. I am a Maths Student at University of Nottingham. Just about to finish my first year. Have exams in may/june. Ok then. introductions over, ill give u a started question:

 

Find all integer solutions for ab=ba given that 0<a<b.

 

Its a really nice question I found in a book. It has a nice solution as well.

 

ooh dont bother with that question. i see that its been asked in other sub forums

 

HEHE

 

anyway later

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Since pple have asked this question before in other forums. ill post my solution to it anyway

 

take a function f where f (x)=ln(x)/x

therefore a^b=b^a if and only if f(a)=f(b). now differentiating f(x) u will find that there is a maximum at x=e. therefore the function f is increasing for x<e and decreasing for x>e. therefore its not possible for both a,b <e or a,b >e cos then f(a) will never be equal to f(b) for a<b

so the only solutions possible is a<e and b>e . now we have 0<a<e. and a is an integer. therefore a=1 or a=2. putting in a=1 we get b=1 which is not a solution as we need a<b. the only other soultion is a=2. puting in a=2 and solving f(b)=f(2) by similar method or however u want we get b =4 . therefore the only solution to a^b=b^a for 0<a<b is a=2,b=4

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Maths is Nottingham is also one of the best if u look at the tables. The timetable is very light though. so thats good. i have a fren who studies maths at imperial. also another frens roommate also does maths. and when i look at the work they get and their timetable, i thank god that i went to nottingham.

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i hope i wont have to do any essays. are u doing a MMath course? apparently the whole 4th year we spend doing a thesis. phew. ill probably do it the night before

 

Yeah, I'm on the MMath. Whether I'll stay on it or not I'll see, but I doubt you'd be doing something that large the night before ;-)

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