Mathematics: Post your doubts here!

[PhoenixAsh12]

You have to use the sum formula
Sn=n/2 (2a+(n-1)d)
in this case n is m
m/2 (2x161+(m-1)x-7)=0
322-7m+7=0
7m=329 m=47

(b) in geometric progression the sum of n terms formula is
a(1-r^n)/(1-r) and sum to infinity formula is a/1-r
s0 this becomes

a(1-r^n)/(1-r)<0.9 a/1-r as sum of n terms <90% of sum to infinity

Thank you!

 

[Dug]

i mean the higest value for it to have an inverse is coming as 2 pi .... not 1.5 pi as in the mark sceheme :S .., plus http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w09_qp_11.pdf how do we draw the 'line' in question 2 and what does the mark scheme mean by the curve flattening at pi :S ?

It is 1.5pi. And what do you mean by 'coming' ? Are you doing calculations for it? You were supposed to deduce it from the graph directly. And are you clear about the concept behind the horizontal test?

 

[roadtrip9o9]

i think i am ... would u mind repeating the concept ?

 

[roadtrip9o9]

http://www.xtremepapers.com/papers/...S Level/Mathematics (9709)/9709_w09_qp_11.pdf how do we draw the 'line' in question 2 and what does the mark scheme mean by the curve flattening at pi :S ?

 

[Dug]

i mean the higest value for it to have an inverse is coming as 2 pi .... not 1.5 pi as in the mark sceheme :S .., plus http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w09_qp_11.pdf how do we draw the 'line' in question 2 and what does the mark scheme mean by the curve flattening at pi :S ?

Come online on skype.

 

[roadtrip9o9]

u here till 20minutes - half an hour ?

 

[Dug]

u here till 20minutes - half an hour ?

Ok

 

[user]

you dont believe me ??
there you go...Proof!
View attachment 7943

Aoa wr wb!

ok...so when the eqn of f(x) is a(x+b)^2 + c...
right..?

i mean did i identify c correct?

 

[Dug]

Aoa wr wb!

ok...so when the eqn of f(x) is a(x+b)^2 + c...
right..?

i mean did i identify c correct?

No, its the x-coordinate of the vertex.

 

[Dug]

Aoa wr wb!

ok...so when the eqn of f(x) is a(x+b)^2 + c...
right..?

i mean did i identify c correct?

And Ws wr wb!!

 

[user]

No, its the x-coordinate of the vertex.

so that means, it's -b ? right?

 

[Dug]

so that means, it's -b ? right?

Exactly.

 

[user]

Exactly.

ok thanks.. jazakAllahu khairen!

and one more thing plz,
in the syllabus, for integration (P1) it says:

​

what are these improper integrals?

 

[Dug]

ok thanks.. jazakAllahu khairen!

and one more thing plz,
in the syllabus, for integration (P1) it says:

View attachment 8689​

what are these improper integrals?

Its the same thing you have been doing till now. No need to fret.
Although, you might want to check out the one that goes up to infinity. I have not seen a question on that in the past papers but, just to be on the safe side, you should know how to evaluate it.

 

[hm12]

I'm sorry for bombarding the thread... My exam's after tomorrow and there's no one/place but here to help...

MJ 07 paper1 question 6- how to find D? I know we find the lengh of BC then equate it to something?

Please help if you have the time I would really appreciate it

find the gradient of AB its 3/2 so as AB is parallel to CD so its gradient will be 3/2 too now find equation of CD using coordinates of C the equation is 2y=3x-30 now solve the equation of BC and CD simultaneously to get the coordinates of D

 

[user]

Its the same thing you have been doing till now. No need to fret.
Although, you might want to check out the one that goes up to infinity. I have not seen a question on that in the past papers but just to be on the safe side you should know how to evaluate it.

haha...that's what...
i just saw this video ....a couple of minutes ago, when i was searching what improper integral actually is

thnx anyway...that video is good...! and I did understand that..

btw i don't see anything improper in the first example in the syllabus...that's a normal one..right?

 

[Dug]

haha...that's what...
i just saw this video ....a couple of minutes ago, when i was searching what improper integral actually is

thnx anyway...that video is good...! and I did understand that..

btw i don't see anything improper in the first example in the syllabus...that's a normal one..right?

The first one is a definite integral. The second one got the infinity sign which makes it improper.

 

[Helpneeded007]

Hi i need help in this question,
1)Whenever a particular gymnast performs a certain routine,the probability that she will do so faultlessly is 0.7.Find to 3 d.p,the probabiliyies that
(a)She will perform the routine faultlessly on more than 4 occasions out of 6
(b)Use a suitable approximation method and justify the approximation method used to evaluate to 3 d.p,the probability that she will perform the routine faultlessly on more than 130 occasions out of 200.
Please help.Thanks alot.

 

[Helpneeded007]

Also need help in this,
1)An unbiased six sided die has numbers 1,1,1,2,2,3 printed on its faces.It is thrown twice.X represents the random variable which is the sum of the scores obtained when the die is thrown twice
(a)Draw a probability distribution table for X
(b)Find the expected value of the total score.
Thx alot for ur help.

 

[Helpneeded007]

Please need help in the 2 questions posted above