Maths

shcndw

Dedicated Member
Oct 29, 2006
1,148
0
0
29
#1
I really shouldn't be making this thread just for this cause but I honestly can't seem to figure this out.

Re-arrange the equation into the form x=?;

e^x = 42

s = ut + 1/2xt^2
 

Tyrien

I'm a real boy!
Jul 8, 2007
12,496
110
0
34
#2
Going to hate this as the first response, but I haven't gone into math for a while.

If memory serves...

x = e√42 ?
 

shcndw

Dedicated Member
Oct 29, 2006
1,148
0
0
29
#4
[QUOTE="Tyrien, post: 0]Going to hate this as the first response, but I haven't gone into math for a while.

If memory serves...

x = e√42 ?[/quote]

Bloody hell, how am I so blind? Thank you very much sir. To be honest, I just spent a lot of time on my homework and got really tired at the end. Thanks!

Added another question. :D
 

Zoibie

Supreme Veteran
Jun 18, 2006
18,368
44
0
29
#5
x = log 42/log e

If your doing A-level ;) And I'm not sure Tyrien's answer is right.

Edit: Oh moving onto the equations of motion I see

x= 2s-2ut all over t^2
 

Tyrien

I'm a real boy!
Jul 8, 2007
12,496
110
0
34
#6
[QUOTE="Zoibie, post: 0]x = log 42/log e

If your doing A-level ;) And I'm not sure Tyrien's answer is right.

Edit: Oh moving onto the equations of motion I see

x= 2s-2ut all over t^2[/quote]

I'm not even sure mine is right! I haven't done a math class for about 4 years now :(

Memory is coming back a little, I trust your answer more as I do... kinda remember using log.

I'm the type who does fine at math so long as it's being used. The formulas and proper methods of solving equations in algebra just fail me after a while.
 

shcndw

Dedicated Member
Oct 29, 2006
1,148
0
0
29
#7
[QUOTE="Zoibie, post: 0]x = log 42/log e

If your doing A-level ;) And I'm not sure Tyrien's answer is right.

Edit: Oh moving onto the equations of motion I see

x= 2s-2ut all over t^2[/quote]

Mind going through it?
 

Zoibie

Supreme Veteran
Jun 18, 2006
18,368
44
0
29
#8
[QUOTE="shcndw, post: 0]Mind going through it?[/quote]

Which one, eh, I'll do both :D

First one

e^x = 42

log e^x = log 42

x log e = log 42

x = log 42/log e

Second

s=ut+1/2xt^2

s-ut=1/2xt^2

2s-2ut=xt^2

2s-2ut (all over) t^2=x

Jyst know if this is homework and you haven't covered it yet, you're going to have some questions to answer :lol:

@Tyrien, yeah I know what you mean, I found it amazing how much I forgot over the 6 weeks of summer holidays.
 

John25

Elite Sage
Apr 8, 2008
10,672
44
48
39
#9
lol ive just started my C&G 2330 electrical course and we have to do crazy maths equations. like this
 

Zoibie

Supreme Veteran
Jun 18, 2006
18,368
44
0
29
#10
[QUOTE="John25, post: 0]lol ive just started my C&G 2330 electrical course and we have to do crazy maths equations. like this
[/quote]

image tags don't work like that, upload the picture to photobucket or imageshack first ;)
 

gster

Paddy McCourt
Mar 13, 2009
3,108
3
0
Bristol
#13
[QUOTE="Zoibie, post: 0]Which one, eh, I'll do both :D

First one

e^x = 42

log e^x = log 42

x log e = log 42

x = log 42/log e

Second

s=ut+1/2xt^2

s-ut=1/2xt^2

2s-2ut=xt^2

2s-2ut (all over) t^2=x

Jyst know if this is homework and you haven't covered it yet, you're going to have some questions to answer :lol:

@Tyrien, yeah I know what you mean, I found it amazing how much I forgot over the 6 weeks of summer holidays.[/quote]

the above is the right answer im sure.

but make sure you remember the "log" zoibie is using is the natural logarithm "ln",

so it can be simplified further from:

x = log 42/log e

to

x = log 42 since log e = ln e = 1
 

holly

Forum Guru
Jul 2, 2008
3,809
5
0
#15
For e^x = 42 is:

x=ln42

In theory you just 'take logs'. e is the inverse of ln. What you do to one side, you have to do to the other. So if you take away the e on one side you have to add a ln on the other side.


The other one is

x=2s - 2ut all over t^2

like zoibie said.
 

gster

Paddy McCourt
Mar 13, 2009
3,108
3
0
Bristol
#16
[QUOTE="holly, post: 0]For e^x = 42 is:

x=ln42

In theory you just 'take logs'. e is the inverse of ln. What you do to one side, you have to do to the other. So if you take away the e on one side you have to add a ln on the other side.


The other one is

x=2s - 2ut all over t^2

like zoibie said.[/quote]

oh, yeah... :lol: thats much simpler than the way i put it


when you have something as simple as e^x = y

then

x = ln y

simple as that, unless they ask specifically to prove that the answer is what it says it is, in which case you take logs and show the working.
 

Mikleran

Elite Member
May 9, 2006
1,926
1
0
40
#20
[QUOTE="gster, post: 0]but make sure you remember the "log" zoibie is using is the natural logarithm "ln"[/quote]

Actually no, you you could use whatever logarithm you wanted because they'd all give the same answer, as long as you use the same logarithm for both "log"s. The "log" button on the calculator, which isn't usually the natural logarithm button, would get the right answer (as would your "ln").
 

ex nihilo7

Master Poster
Nov 13, 2006
3,373
11
38
#22
[QUOTE="shcndw, post: 0]Thank you all for your help. This is for Physics and it was my first homework.[/quote]
If you need any other help just post here. I'm pretty decent at physics.
 

Zoibie

Supreme Veteran
Jun 18, 2006
18,368
44
0
29
#26
[QUOTE="smiggy, post: 0]AS ;)[/quote]

Or A-level maths if you do Maths Mechanics i.e. redoing some parts of Physics :p
 

shcndw

Dedicated Member
Oct 29, 2006
1,148
0
0
29
#27
Already gave out too much rep today. :(

For the people who have already experienced Physics, is there anything I need to know? Is it really hard? Required a lot of revision? A lot of complex concepts?

How much effort do I have to input to achieve an A grade?
 

adz1992

Elite Member
Nov 30, 2005
1,560
3
0
#28
[QUOTE="smiggy, post: 0]AS ;)[/quote]

be thankful though its AS physics and not actual AS level mathematics, its crazy hard :(


EDIT: most of the traditional subjects (maths english history sciences etc) are all harder then the none traditional simply because of the leap as you are expected to know the basics. to get the A grade (or higher if you started this year as the A* grade was introduced this year) you will have to work very hard unless you have a natural knack for physics.
 

Zoibie

Supreme Veteran
Jun 18, 2006
18,368
44
0
29
#29
[QUOTE="shcndw, post: 0]Already gave out too much rep today. :(

For the people who have already experienced Physics, is there anything I need to know? Is it really hard? Required a lot of revision? A lot of complex concepts?

How much effort do I have to input to achieve an A grade?[/quote]

It really depends how well you understand what you're getting taught. I understood it really well, didn't do much revision (aside from lots of practise papers in class) and got an A.

The maths part of it isn't all that hard, at least it isn't for me. In fact, I don't think I've ever used logs or Calculus at all in Physics. PLus most of the equations are give on the data sheet, it's really just the theory you need to understand.
 

gster

Paddy McCourt
Mar 13, 2009
3,108
3
0
Bristol
#30
[QUOTE="shcndw, post: 0]Already gave out too much rep today. :(

For the people who have already experienced Physics, is there anything I need to know? Is it really hard? Required a lot of revision? A lot of complex concepts?

How much effort do I have to input to achieve an A grade?[/quote]

i would say the same as zoibie. it depends, i just felt that physics came easy to me. I enjoyed maths and physics :rolleyes: and i guess that helps in understand (if you feel motivated).

Then again, if i found something tough, i managed to teach myself stuff quite easily too, but that was never necessary in physics since i just found it easy.

The fact of the matter is, irrelevant of wether you feel you learn it easily or not doesnt mean anything. If you put in the time and work hard at it, there is no doubt you can get an A.