Post your AS-Level Mathematics (P1 and M1) doubts here.

[hellblender]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s13_qp_11.pdf
Question no,1 , how do you know if a function is increasing or decreasing and how do you prove it?
question 5 , how do you solve for the angle?
Any type of help appreciated.

dy/dx>o for an icreasing function.
dy/dx<0 for decreasing

in the case of the question, your dy/dx>0 for all real numbers of x so all you need to do is prove that your dy/dx will always be positive for whatever real number x is subbed in.

 

[Xerav43]

dy/dx>o for an icreasing function.
dy/dx<0 for decreasing
in the case of the question, your dy/dx>0 for all real numbers of x so all you need to do is prove that your dy/dx will always be positive for whatever real number x is subbed in.

Thanks for your answer.
So I get the derivative , and if it's bigger than 0 it's an increasing function and vice versa

but how do I prove on the answer sheet that dy/dx > 0 , like in the example of dy/dx = 6(2x-5)^2 + 1 , how do I prove that it will always be positive?

 

[Syeda Rida Rizvi]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s13_qp_11.pdf
Question no,1 , how do you know if a function is increasing or decreasing and how do you prove it?
question 5 , how do you solve for the angle?
Any type of help appreciated.

A function is decreasing if the gradient is decreasing and vice versa ..dy/dx krke prove krdou ya phir make the graph.
And the other ques.. Iska answer btadou mjhy phir i'll post the pics! will save me some embarrassment agar ghalat hua xD

 

[Syeda Rida Rizvi]

Dude your a genius man in sha allah all A*'s for you

thanks for this answer btw

Thankyou buddy. And my pleasure. Insha'Allah we'll all end up with good grades.

 

[Xerav43]

A function is decreasing if the gradient is decreasing and vice versa ..dy/dx krke prove krdou ya phir make the graph.
And the other ques.. Iska answer btadou mjhy phir i'll post the pics! will save me some embarrassment agar ghalat hua xD

Thank you.

 

[hellblender]

Thanks for your answer.
So I get the derivative , and if it's bigger than 0 it's an increasing function and vice versa

but how do I prove on the answer sheet that dy/dx > 0 , like in the example of dy/dx = 6(2x-5)^2 + 1 , how do I prove that it will always be positive?

You will see in the question that when you get your dy/dx, it has to be >0. Simply because in that fraction you'll obtain for this particular question, the top is a positive number and the bottom is in brackets squared , which means it has to be positive. Hence it's >0 and increasing.

So you'll just have to complete the dy/dx first and then try to prove to the examiner from there this way.

Do NOT subsitute random numbers into the equation, like a random real number, this may prove it's >0 for that particular number, but according to examiner reports they want you to prove it in a way i mentioned above, besides, you can't possibly sub every real number there is in there to prove it's >0. I made the mistake of subbing x=1 into it but lost marks that way.

Hope that clears it up.

 

[Syeda Rida Rizvi]

Thank you.

Here
Thank me when u do good in the paper.

 

[Syeda Rida Rizvi]

BEST OF LUCK, EVERYBODY! (Y)
Remember me in your prayers.
Allah Hafiz.

 

[Xerav43]

Here
Thank me when u do good in the paper.

I'll thank you now and then haha!
Thanks alot.

 

[Thought blocker]

All the very best, do well, Keep calm.

 

[SitiPutri]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w12_qp_11.pdf

q11)iii
we have to find the equations of OA and BC in order to find coordinates of E right?
i did that, but i am getting x as 10/13 and y as 20/13
can someone check my workings and tell me where i went wrong?
its the top part, ignore the bottom part

Wrong gradient. M of BC is -3/4

 

[mak kings]

You will see in the question that when you get your dy/dx, it has to be >0. Simply because in that fraction you'll obtain for this particular question, the top is a positive number and the bottom is in brackets squared , which means it has to be positive. Hence it's >0 and increasing.

So you'll just have to complete the dy/dx first and then try to prove to the examiner from there this way.

Do NOT subsitute random numbers into the equation, like a random real number, this may prove it's >0 for that particular number, but according to examiner reports they want you to prove it in a way i mentioned above, besides, you can't possibly sub every real number there is in there to prove it's >0. I made the mistake of subbing x=1 into it but lost marks that way.

Hope that clears it up.

but bro cant v just subtittue the DOMAIN value ,and thus prove it???????

 

[M.Shahzaib Shoaib]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w13_qp_13.pdf


4 (1)

 

[SherlockHolmes221B]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w13_qp_13.pdf


4 (1)

OD = 4i +3j
CD = 4i + 3j - 10k (basically the same as OD but you'll have to go down from C to 0 -10k)

 

[M.Shahzaib Shoaib]

OD = 4i +3j
CD = 4i + 3j - 10k (basically the same as OD but you'll have to go down from C to 0 -10k)

Bro or sister..

Can you explain the working which goes into this particular specified question ..

Really confused with how to find OD ..

 

[SherlockHolmes221B]

Bro or sister..

Can you explain the working which goes into this particular specified question ..

Really confused with how to find OD ..

Sister
OD is found by moving halfway through OA, which is 4i (seeing that the full length of it is 8)
When your halfway through it, you can go from this point to D by following the j direction also by half because you're not moving the point with the entire length, only by half of it. Therefore, you'll use 3, not 6.
This will result in OD being 4i+3j
Hope I helped! That question is sorta confusing, so don't stress yourself ^__^

 

[M.Shahzaib Shoaib]

Well I hope this doesn't appear for the exam .. O

Anyways thanks ..

 

[M.Shahzaib Shoaib]

Btw!

How do we know that a function is one-one or not ?

 

[mak kings]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w12_qp_13.pdf11 (iv) plzzzzzzz sm1 explain this .. its vurgent!!

 

[David Hussey]

Wrong gradient. M of BC is -3/4

got it thnx!