You are Here: Home >< Maths

# Graphs and asymptotes, c3/c4

Announcements Posted on
Four hours left to win £100 of Amazon vouchers!! Don't miss out! Take our short survey to enter 24-10-2016
1. For part b) there is an asymptote at y=0 so how can the graph have two roots?? Could someone explain the understanding to me please.
2. You've misunderstood the question. It is asking for the set of values of y (values that k can take) for there to be 2 roots.

A root here will be where y=k and y=f(x) intersect.
3. From what i see, its specifically saying the function f(x) = k has two roots, and its not referring to the graph of y = f(x).
4. (Original post by Parallex)
You've misunderstood the question. It is asking for the set of values of y (values that k can take) for there to be 2 roots.

A root here will be where y=k and y=f(x) intersect.
(Original post by MAS98)
From what i see, its specifically saying the function f(x) = k has two roots, and its not referring to the graph of y = f(x).
I don't think I get it. How would I find k in this case?

I've come across the same question from another paper and I'm stumped again.
5. (Original post by Ravster)
I don't think I get it. How would I find k in this case?

I've come across the same question from another paper and I'm stumped again.
You're right y=0 is an asymptote so for f(X)=k we know that k must be a negative so when we subtract k to both sides f(X) +k it shifts the curve upwards. The range where the curve will intersect the X axis twice (two solutions) will be between 0 since it's an asymtpote and at your minimum point from (a) since translating the curve upwards by more than your minimum point will leave you with 0 solutions.

## Register

Thanks for posting! You just need to create an account in order to submit the post
1. this can't be left blank
2. this can't be left blank
3. this can't be left blank

6 characters or longer with both numbers and letters is safer

4. this can't be left empty
1. Oops, you need to agree to our Ts&Cs to register

Updated: May 28, 2016
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:
Today on TSR

### Who is getting a uni offer this half term?

Find out which unis are hot off the mark here

Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read here first

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams