Hey there! Sign in to join this conversationNew here? Join for free
 You are Here: Home >< Maths

# limits, are they right? Watch

1. Hi,

Are my answers correct?

Q1) lim x --> 9
x - 9 / -3
My answer = 9

Q2) lim a -->-5
+ -10a /( a+5)
My answers: a= 2 and a=0

Q3) lim a--> 0
() / ( - )
Thats (a power third) divided by (a squared - 2a to third)
My answer = -0.5

thanks!
2. (Original post by dream123)
Hi,

Are my answers correct?

Q1) lim x --> 9
x - 9 / -3
My answer = 9

Q2) lim a -->-5
+ -10a /( a+5)
My answers: a= 2 and a=0

Q3) lim a--> 0
() / ( - )
Thats (a power third) divided by (a squared - 2a to third)
My answer = -0.5

thanks!
http://www.wolframalpha.com/

This website solves limits directly. Enter like this "limit as x tends to 9 of (x-9)/(sqrt(x)-3)".

Btw, q1 is actually 6.
3. (Original post by Don John)
http://www.wolframalpha.com/

This website solves limits directly. Enter like this "limit as x tends to 9 of (x-9)/(sqrt(x)-3)".

Btw, q1 is actually 6.
I've just used the L'hospital's method of simply differentiation and my answers are correct
Only problem is, my question has 10 marks-do you think l'hospitals method is work 10 marks? :/
Thanks
4. (Original post by dream123)
I've just used the L'hospital's method of simply differentiation and my answers are correct
Only problem is, my question has 10 marks-do you think l'hospitals method is work 10 marks? :/
Thanks
Use the method that you've been taught in lectures. If you don't know, simply email your lecturer and ask what method is usually accepted in this module.
5. (Original post by dream123)
Are my answers correct?
I don't think so:

Q1) lim x --> 9
x - 9 / -3
My answer = 9
How did you get 9 as your answer? I don't think it's right.

Q2) lim a -->-5
+ -10a /( a+5)
My answers: a= 2 and a=0
What do you mean 'a=...'? You're not trying to find a, you're trying to find the limit of the fraction as . There is only one limit, not two, so you definitely shouldn't have 2 limits here.

Q3) lim a--> 0
() / ( - )
Thats (a power third) divided by (a squared - 2a to third)
My answer = -0.5
I agree with this answer.

By the looks of it, Q1,2 are L'Hôpital's rule questions, and Q3 just requires you to rearrange the fraction to find the limit.
6. (Original post by nuodai)
I don't think so:

How did you get 9 as your answer? I don't think it's right.

What do you mean 'a=...'? You're not trying to find a, you're trying to find the limit of the fraction as . There is only one limit, not two, so you definitely shouldn't have 2 limits here.

I agree with this answer.

By the looks of it, Q1,2 are L'Hôpital's rule questions, and Q3 just requires you to rearrange the fraction to find the limit.
I figured it out, so all is well

Reply
Submit reply
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: December 15, 2010
Today on TSR

### Degrees to get rich!

... and the ones that won't

### Cambridge interviews pour in...

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

## Make your revision easier

### 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

Can you help? Study help unanswered threads

## 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.