You are Here: Home

# AS C1 Quadratic Equations/Inequalites Help

Maths and statistics discussion, revision, exam and homework help.

Announcements Posted on
1. AS C1 Quadratic Equations/Inequalites Help
Hi, so I have an exam tomorrow and was going through some questions and was lost on a few of them so if you could help me that would be greatly appreciated.

1) Given that show that

That I completely couldn't do. And then it has a part b) Solve the simultaneous equation: &

For that I got & . So if then the answer would be although the answers said it is wrong. Oh I did this via substitution.

2) Find the set of values for which which I did and got to a quadratic inequality of which is unsolvable via factorisation (or am I just being plain dumb?), and I guessed that that should be the method used considering it is for the other question but the answers are meant to be whole numbers.

3) Use algebra to find the set of values of x for which which I did to get the correct answer of or . This then has a follow up question which I completely can't do which is: Using your answer to the previous part find the set of values of for which .

Thanks!! Any help would be greatly appreciated.
2. Re: AS C1 Quadratic Equations/Inequalites Help
Bump?
3. Re: AS C1 Quadratic Equations/Inequalites Help
In the first one is it 3 to the power of x , and 9 to the power of y-1 ?
4. Re: AS C1 Quadratic Equations/Inequalites Help
(Original post by rmpr97)
Hi, so I have an exam tomorrow and was going through some questions and was lost on a few of them so if you could help me that would be greatly appreciated.

1) Given that show that

That I completely couldn't do. And then it has a part b) Solve the simultaneous equation: &

For that I got & . So if then the answer would be although the answers said it is wrong. Oh I did this via substitution.

2) Find the set of values for which which I did and got to a quadratic inequality of which is unsolvable via factorisation (or am I just being plain dumb?), and I guessed that that should be the method used considering it is for the other question but the answers are meant to be whole numbers.

3) Use algebra to find the set of values of x for which which I did to get the correct answer of or . This then has a follow up question which I completely can't do which is: Using your answer to the previous part find the set of values of for which .

Thanks!! Any help would be greatly appreciated.
What's the relationship of 3 and 9? Try writing 9 as

Not sure how you ended up with that inequality... I'm getting

For the last part, just sub in ?
Last edited by Arva; 26-09-2012 at 19:26.
5. Re: AS C1 Quadratic Equations/Inequalites Help
(Original post by Arva)
What's the relationship of 3 and 9? Try writing 9 as

Not sure how you ended up with that inequality... I'm getting

For the last part, just sub in ?
Do you mean -20 for question 2?
6. Re: AS C1 Quadratic Equations/Inequalites Help
(Original post by Arva)
What's the relationship of 3 and 9? Try writing 9 as

Not sure how you ended up with that inequality... I'm getting

For the last part, just sub in ?
I'm not sure what the relationship is, all the info given is that.

And with the inequality it's probably me making silly mistakes then.

Also in regards to the last part, I'm not sure that's correct because wouldn't that lead to them getting the same solutions although the textbooks says or
7. Re: AS C1 Quadratic Equations/Inequalites Help
(Original post by Haesights)
Do you mean -20 for question 2?
Thanks for pointing out the typo, I do indeed.
8. Re: AS C1 Quadratic Equations/Inequalites Help
(Original post by rmpr97)
I'm not sure what the relationship is, all the info given is that.

And with the inequality it's probably me making silly mistakes then.

Also in regards to the last part, I'm not sure that's correct because wouldn't that lead to them getting the same solutions although the textbooks says or [/latex] y>3 [latex]
You don't need to be given info on the relationship between 3 and 9

Think of 9 as 3^2 - now they're both powers of three so you can equate them.

If y^2 equals x, square rooting the solutions gives both a non-real answer (ignore this, it isn't a valid solution at this stage), and -3 and 3 (the roots of 9.
Last edited by Arva; 26-09-2012 at 19:27.
9. Re: AS C1 Quadratic Equations/Inequalites Help
(Original post by rmpr97)
Hi, so I have an exam tomorrow and was going through some questions and was lost on a few of them so if you could help me that would be greatly appreciated.

1) Given that show that

That I completely couldn't do. And then it has a part b) Solve the simultaneous equation: &

For that I got & . So if then the answer would be although the answers said it is wrong. Oh I did this via substitution.

2) Find the set of values for which which I did and got to a quadratic inequality of which is unsolvable via factorisation (or am I just being plain dumb?), and I guessed that that should be the method used considering it is for the other question but the answers are meant to be whole numbers.

3) Use algebra to find the set of values of x for which which I did to get the correct answer of or . This then has a follow up question which I completely can't do which is: Using your answer to the previous part find the set of values of for which .

Thanks!! Any help would be greatly appreciated.
for the first question you just have to change 9 in to a power of 3. Remember whatever is on the left side MUST equal what's on the right.
10. Re: AS C1 Quadratic Equations/Inequalites Help
(Original post by Arva)
You don't need to be given info on the relationship between 3 and 9

Think of 9 as 3^2 - now they're both powers of three so you can equate them.

If y^2 equals x, square rooting the solutions gives both a non-real answer (ignore this, it isn't a valid solution at this stage), and -3 and 3 (the roots of 9.
So the first one ? then complete the rest of it?

Also the second one I don't get. If you make doesn't that make it the same inequality the first one? or you just make so then you get ?
Last edited by rmpr97; 26-09-2012 at 19:35.
11. Re: AS C1 Quadratic Equations/Inequalites Help
(Original post by rmpr97)
So the first one ? then complete the rest of it?

Also the second one I don't get. If you make doesn't that make it the same inequality the first one? or you just make so then you get ?
At that stage you're done. You've proven that , so the powers must equate.

The original is , not .

You already have solutions for x, so just sub y^2 = x and root them.
12. Re: AS C1 Quadratic Equations/Inequalites Help
(Original post by Arva)
At that stage you're done. You've proven that , so the powers must equate.

The original is , not .

You already have solutions for x, so just sub y^2 = x and root them.
Ahh I finally get it now! Thankyou so much.

So with the solutions from the first part I plug them into the equation in place of y^2.
13. Re: AS C1 Quadratic Equations/Inequalites Help
(Original post by rmpr97)
Ahh I finally get it now! Thankyou so much.

So with the solutions from the first part I plug them into the equation in place of y^2.
No problem

Save yourself some time, you already have the solutions... You know that ...

Sub in y^2

## Step 2: Register

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

this is what you'll be called on TSR

2. this can't be left blank

never shared and never spammed

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. By completing the slider below you agree to The Student Room's terms & conditions and site rules

2. Slide the button to the right to create your account

You don't slide that way? No problem.

Last updated: September 26, 2012
Study resources
Moderators

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

This forum is moderated by:
Reputation gems:
You get these gems as you gain rep from other members for making good contributions and giving helpful advice.
Post rating score:
These scores show if a post has been positively or negatively rated by our members.