Mathematics: Post your doubts here!

[Maayee]

can someone help me with this.... question 3 pls
http://papers.xtremepapers.com/CIE/...AS Level/Mathematics (9709)/9709_s04_qp_3.pdf

 

[Maayee]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s10_qp_31.pdf
and also question 9

 

[musiclover gurl]

Express 9x^2 - 36x +52 in the form (Ax^2 - B) + C, where A, B and C are integers. Hence, or otherwise find the set of values taken by 9x^2 - 36x +52 for x ∈ R.
Help please?

 

[The Sarcastic Retard]

Express 9x^2 - 36x +52 in the form (Ax^2 - B) + C, where A, B and C are integers. Hence, or otherwise find the set of values taken by 9x^2 - 36x +52 for x ∈ R.
Help please?

9(x^2 - 4x + 52/9)]
9[(x - 2)^2 + 16/9)]
9(x - 2)^2 + 16
3^2 (x - 2)^2 + 16
(3x - 6)^2 + 16
--> 16

 

[musiclover gurl]

9(x^2 - 4x + 52/9)]
9[(x - 2)^2 + 16/9)]
9(x - 2)^2 + 16
3^2 (x - 2)^2 + 16
(3x - 6)^2 + 16
--> 16

Thanks for replying. But I used another method, the comparison of coefficients, to put it in the required form and thus when comparing I gained two values of A(there was a square root). This is what is confusing me as to what value should I take?
And by set of values, does the question mean the range?

 

[The Sarcastic Retard]

Thanks for replying. But I used another method, the comparison of coefficients, to put it in the required form and thus when comparing I gained two values of A(there was a square root). This is what is confusing me as to what value should I take?
And by set of values, does the question mean the range?

SHow me your paper, and Temme which paper it is..
According to me they are talking about range.

 

[musiclover gurl]

No...it is of a year 86....a very old question...found it in a book!
Also due to A having two values, even B will end up having two values!! I hope you can solve this mystery

 

[The Sarcastic Retard]

No...it is of a year 86....a very old question...found it in a book!
Also due to A having two values, even B will end up having two values!! I hope you can solve this mystery

From your this expression : (Ax)^2 - 2ABx + B^2 + C, clearly A = 3. If u took A as -3 then 36/(2 x -3) = -6 and that will make the opposite sign of what we need that is +ve sign and we need -ve. If u take A = 3 then, B = 6. So its correct now.
More over as its squared, hence f(x) >= 16

 

[musiclover gurl]

From your this expression : (Ax)^2 - 2ABx + B^2 + C, clearly A = 3. If u took A as -3 then 36/(2 x -3) = -6 and that will make the opposite sign of what we need that is +ve sign and we need -ve. If u take A = 3 then, B = 6. So its correct now.
More over as its squared, hence f(x) >= 16

Thank you! and sorry for the late reply

 

[musiclover gurl]

Given that x^2 + 2x + A is positive for all values of x, find set of values of A.
Help please?
(This question is not from any past paper, it is from a book.)

 

[The Sarcastic Retard]

Given that x^2 + 2x + A is positive for all values of x, find set of values of A.
Help please?
(This question is not from any past paper, it is from a book.)

b^2 - 4ac > 0
4 - 4a > 0
4 > 4a
a < 1

 

[Paruna]

b^2 - 4ac > 0
4 - 4a > 0
4 > 4a
a < 1

If it's positive b^2-4ac should not be less than zero? Since, if the function is positive, this implies that it must lie completely above the x-axis- i.e. It will have no solution wrt the x-axis, right? That means b^2 -4ac < 0 ? Am I right here?

 

[The Sarcastic Retard]

If it's positive b^2-4ac should not be less than zero? Since, if the function is positive, this implies that it must lie completely above the x-axis- i.e. It will have no solution wrt the x-axis, right? That means b^2 -4ac < 0 ? Am I right here?

Ya

 

[Paruna]

Ya

A should be greater than 1?

 

[The Sarcastic Retard]

Y

A should be greater than 1?

ya

 

[musiclover gurl]

If it's positive b^2-4ac should not be less than zero? Since, if the function is positive, this implies that it must lie completely above the x-axis- i.e. It will have no solution wrt the x-axis, right? That means b^2 -4ac < 0 ? Am I right here?

Thank you

 

[musiclover gurl]

Y

ya

Thanks

 

[Dark Destination]

What are the best books for A-Level mathematics for P1, P3, M1 and S1?

Need to buy a book now, a couple of months left in exams.

 

[Rizwan Javed]

What are the best books for A-Level mathematics for P1, P3, M1 and S1?

Need to buy a book now, a couple of months left in exams.

Advanced Level Mathematics : Pure Mathematics 2 & 3 by Hugh Neill and Douglas Quadling
Advanced Level Mathematics : Pure Mathematics 1 by Hugh Neill and Douglas Quadling
A concise coure in Advanced Level Statistics (with worked examples) by J. Crawshaw and J.Chambers ( this book covers both S1 and S2 so check syllabus to know which contents to study for S1 )

btw isn't it too early to buy the books ?

 

[Dark Destination]

Advanced Level Mathematics : Pure Mathematics 2 & 3 by Hugh Neill and Douglas Quadling
Advanced Level Mathematics : Pure Mathematics 1 by Hugh Neill and Douglas Quadling
A concise coure in Advanced Level Statistics (with worked examples) by J. Crawshaw and J.Chambers ( this book covers both S1 and S2 so check syllabus to know which contents to study for S1 )

btw isn't it too early to buy the books ?

Thanks! ^^

Lol, I know. I've been delaying buying the books for an entire year.