I require help with a bit of maths

pinkacidbootson · 9 Jan 2007 at 03:14

How do i get from:

e^0.003t - e^0.002t = 0.08

to:

e^0.001t - 1 = 0.08e^-0.002t

I have a feeling it's blindingly obvious, but im just not seeing it! Over to you, OcUK

Meeark · 9 Jan 2007 at 03:41

Simple rule is

A^x . A^y = A^(x+y)

All they have done is extracted e^0.002t from each term.

e^0.003t / e^0.002t = e^(0.003t-0.002t) = e^0.001t

Alex_L · 9 Jan 2007 at 03:46

Meeark said:
Simple rule is

A^x . A^y = A^(x+y)

All they have done is extracted e^0.002t from each term.

e^0.003t / e^0.002t = e^(0.003t-0.002t) = e^0.001t

Think you mean A^xy = (A^x)^y for this problem

Meeark · 9 Jan 2007 at 03:47

Umm don't think I do(well did) OP has now changed the equation and is incorrect in its current form.

pinkacidbootson · 9 Jan 2007 at 03:51

Yes sorry i made a mistake and changed it slightly. Thanks for the help though. I think the equation i typed originally was an intermediate step.. or something. 4 hours of maths makes me tired

Alex_L · 9 Jan 2007 at 03:51

Looks like i'm wrong. Too much damn organic chemistry floating about in my head

pinkacidbootson · 9 Jan 2007 at 04:01

All i had to do was divide by e^0.002t, durrrr

Now time for coffee! Yay!

Smithy · 9 Jan 2007 at 04:10

Johanson said:
All i had to do was divide by e^0.002t, durrrr

Thats ok for the LHS, but how does 0.08 devided by e^0.002t come to 0.08^-0.002t?

Or is it just another one of those random rules with exponentials? ("because it just does")

pinkacidbootson · 9 Jan 2007 at 04:15

You know what, i may be totally wrong on that bit :confused:

but i thought that a/x^b = ax^-b ?

In fact yes that's correct, which explains how i got the RHS.

Smithy · 9 Jan 2007 at 04:33

So wouldnt it then be;

e^0.001t - 1 = 0.08e^-0.002t

?

pinkacidbootson · 9 Jan 2007 at 04:43

Yes it should be but i seem to have missed out the 'e' on the RHS, spelling mistake! But the maths is sorted now.

pinkacidbootson · 10 Jan 2007 at 18:15

Please help, my brain has stopped working

I need to differentiate the following:

y = e^2/x + e^x

I know the chain, product and quotient rules, but this simple question is taking forever and getting me nowhere.

Again, i imagine the answer to be blindingly obvious. Could someone point me in the right direction please?

benktlottie · 10 Jan 2007 at 18:20

Dont you just love cheating to get good grades!

Enfield · 10 Jan 2007 at 18:21

Johanson said:
How do i get from:

e^0.003t - e^0.002t = 0.08

to:

e^0.001t - 1 = 0.08e^-0.002t

I have a feeling it's blindingly obvious

Yeah, if you're a rocket scientist.

What the hell is it all about?

pinkacidbootson · 10 Jan 2007 at 18:22

Hows it cheating? Its not like im sat in exam right now, i just need to answer this to move onto the next part of the question. Its not homework either, just revision. Same as asking a tutor.. so, be my tutor

Enfield said:
Yeah, if you're a rocket scientist.

What the hell is it all about?

2 months ago i would have said the same thing

Vixen · 10 Jan 2007 at 19:11

Johanson said:
I need to differentiate the following:

y = e^2/x + e^x

I know the chain, product and quotient rules, but this simple question is taking forever and getting me nowhere.

Again, i imagine the answer to be blindingly obvious. Could someone point me in the right direction please?

e^x differentiates as e^x. Rearrange the first term to be e^2.(x^-1), where e^2 is a constant and you're left with a very simple differentiation.

Killa_ken · 10 Jan 2007 at 19:13

man i hate math

pinkacidbootson · 10 Jan 2007 at 19:15

Vixen said:
Rearrange the first term to be e^2.(x^-1), where e^2 is a constant

That's what i was missing, thanks

Smithy · 10 Jan 2007 at 22:29

Core 3 A-Level maths by chance Johanson?

Dave · 10 Jan 2007 at 22:47

Killa_ken said:
man i hate math

Maths.