Mathematics: Post your doubts here!

[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.

 

[Layla..]

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.

Since you had taken add-maths in O-levels, you don't even need to study for P1. As far as stats is concerned, the books have nothing good to offer. I suggest you do not buy books for anything. Dive straight into the past papers and the internet can help you with the course
When are you giving your Math exam?
I'm done with P1 and S1, got M1 and P3 this M/J

 

[Dark Destination]

Since you had taken add-maths in O-levels, you don't even need to study for P1. As far as stats is concerned, the books have nothing good to offer. I suggest you do not buy books for anything. Dive straight into the past papers and the internet can help you with the course
When are you giving your Math exam?
I'm done with P1 and S1, got M1 and P3 this M/J

Have to give all four P1, P3, M1, S1 in May-June 2016.