You are Here: Home >< Maths

# Set of values (C1) watch

1. Hi all, just a quick question about a C1 maths past paper question. I'm not entirely sure how to go about answering this question, anyway here it is.
Find the set of values of for which the graph of does not intersect the axis.
Any help on how to answer this question or the method I should use will be much appreciated.
2. When a parabola does not intersect the x axis, the discriminant of the quadratic will be negative.
3. (Original post by biologeek)
Hi all, just a quick question about a C1 maths past paper question. I'm not entirely sure how to go about answering this question, anyway here it is.
Find the set of values of for which the graph of does not intersect the axis.
Any help on how to answer this question or the method I should use will be much appreciated.
I believe this means that the curve does not cross the x-axis, so therefore

Input the values which give us

Which means

4. (Original post by MashB)
I believe this means that the curve does not cross the x-axis, so therefore

Input the values which give us

Which means

No. That isn't how you solve quadratic inequalities.
5. (Original post by Mr M)
No. That isn't how you solve quadratic inequalities.
How do you?

This was posted from The Student Room's iPhone/iPad App
6. (Original post by MashB)
How do you?
The easiest way is to graph the inequality.

means

Sketch

Check which values of k produce negative values of y.
7. (Original post by Mr M)
The easiest way is to graph the inequality.

means

Sketch

Check which values of k produce negative values of y.
(Just checking) ?
8. (Original post by McLH)
(Just checking) ?
Yes.
9. (Original post by Mr M)
Yes.
So in a way I was on the right track, just didnt finish it...

and
so plot them on the graph and then that becomes
10. (Original post by MashB)
So in a way I was on the right track, just didnt finish it...
That does not lead to this

The first line is not possible
11. (Original post by TenOfThem)
That does not lead to this

The first line is not possible
Could you explain it, I'm confusing myself here now.

This was posted from The Student Room's iPhone/iPad App
12. (Original post by MashB)
Could you explain it, I'm confusing myself here now.
You go from

to

there are no intermediate lines
13. (Original post by TenOfThem)
You go from

to

there are no intermediate lines
I meant as in explain the answer to op's question.

This was posted from The Student Room's iPhone/iPad App
14. (Original post by MashB)
I meant as in explain the answer to op's question.

not sure what else you want
15. (Original post by MashB)
Could you explain it, I'm confusing myself here now.

This was posted from The Student Room's iPhone/iPad App
I know I shouldn't post full solutions, but for benefit:

Divide by 4

Plot
16. (Original post by McLH)

This line is incorrect
17. (Original post by TenOfThem)
This line is incorrect
As a solution, but to show where the roots are that I'm plotting before i do a sketch of the graph is it? If so, what should I write?
18. (Original post by McLH)
As a solution, but to show where the roots are that I'm plotting before i do a sketch of the graph is it? If so, what should I write?
The answer that I gave in post 12

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: January 7, 2013
Today on TSR

### Congratulations to Harry and Meghan!

But did you bother to watch?

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