You are Here: Home >< Maths

1. Guys as you know l am no maths person at all so l just want to check whether l am on the right lines with this question or way off, l actually have 2 answers and 2 completely different ways of doing this so l'll write this one out first and you can all give me your tuppence worth if you wouldn't mind helping an non maths person out please!

Let F be a function of t. When log10 F is plotted against t, the graph is a straight line. Furthermore, log10 F=3,5 when t=2 and log10 F=6 when t =5. Find an expression for F in terms of t that does not involve logarithms.

Solution 1

diff of logs 6 -3.5
--------------------- 2.4/3 = 0.83
diff of logs 5 -2

Thus the line has the slope 0.83 and passes through the point t2
Thus the line has the equation log10 F -3.5 = 0.83 (t-2)

0.83 - 2* 0.83 =0.83 + 3.5-1.66
= 0.83 +1.84

then raise the powers 10^0.83 * 10^ 1.84

F = 69.2 * (6.8)t

Is this right or not?

2. (Original post by Karen72)
Guys as you know l am no maths person at all so l just want to check whether l am on the right lines with this question or way off, l actually have 2 answers and 2 completely different ways of doing this so l'll write this one out first and you can all give me your tuppence worth if you wouldn't mind helping an non maths person out please!

Let F be a function of t. When log10 F is plotted against t, the graph is a straight line. Furthermore, log10 F=3,5 when t=2 and log10 F=6 when t =5. Find an expression for F in terms of t that does not involve logarithms.

Solution 1

diff of logs 6 -3.5
--------------------- 2.4/3 = 0.83
diff of logs 5 -2

Thus the line has the slope 0.83 and passes through the point t2
Thus the line has the equation log10 F -3.5 = 0.83 (t-2)

0.83 - 2* 0.83 =0.83 + 3.5-1.66
= 0.83 +1.84

then raise the powers 10^0.83 * 10^ 1.84

F = 69.2 * (6.8)t

Is this right or not?

not sure what "diff of logs" is getting at, but I'd advise you to keep the exact value of the slope, i.e

Now, you get

so

so

Hint:

because

3. (Original post by Indeterminate)
not sure what "diff of logs" is getting at, but I'd advise you to keep the exact value of the slope, i.e

Now, you get

so

so

Hint:

because

The above is what we've been taught and l've no idea if the question l've done is the same thing as l said before the maths lecturer was sacked and we're 4 weeks from exams on a subject that is not my area at all, l am actually an Anatomy student l know hee haw about about Maths on any level so l really need some help!

Thanks for the help btw l really do appreciate it!
4. (Original post by Karen72)

The above is what we've been taught and l've no idea if the question l've done is the same thing as l said before the maths lecturer was sacked and we're 4 weeks from exams on a subject that is not my area at all, l am actually an Anatomy student l know hee haw about about Maths on any level so l really need some help!

Thanks for the help btw l really do appreciate it!
What's shown in the pic is correct, but I 'd say it's a bit lazy as they haven't maintained the exact values.

Take this example. Here,

so it wold be better to keep it as a fraction rather than approximate it to 0.83.

However, if it's acceptable on your course, you may approximate like that.

Make sense?
5. (Original post by Indeterminate)
What's shown in the pic is correct, but I 'd say it's a bit lazy as they haven't maintained the exact values.

Take this example. Here,

so it wold be better to keep it as a fraction rather than approximate it to 0.83.

However, if it's acceptable on your course, you may approximate like that.

Make sense?

Yup that makes sense as l said he was sacked for being an idiot and over complicating stuff so l don't really have any faith in his notes!

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: March 30, 2013
Today on TSR

### Falling in love with him

But we haven't even met!

### Top study tips for over the Christmas holidays

Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams

## Groups associated with this forum:

View associated groups
Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.