Mathematics: Post your doubts here!

[iKhaled]

Hello everyone
I am new to this part of Xtremepapers cuz i hv just finished my O levels n in these vacations i wanna study for A levels .Although i created a thread but there was no reply. Actually i need the name of the best books for Math A levels that most renown skools follow.

hey man, use this site will prepare u very well for the maths papers

http://www.examsolutions.net/

 

[waleedsmz]

Hi I'm having trouble in trigonometric identities, can someone please help me with this question:

View attachment 29030

( s+c ) ( 1 - s c )

Expand the brackets:
s + c - s^2 c - s c^2
Using identities s^2 + c^2 =1
s + c - (1 - c^2 )c - s(1-s^2)
Do the calculations, it'd give the required form.

 

[waleedsmz]

Hello,

could you help me please? I'm having a hard time with number 5 (iii). I have got 2sec^2X - 1 - 2 secXtanX. There is a sign problem. :$
Please help me.

Similar to the question above that one, you'd simply have to expand ( sec + tan ) ^2
sec^2 + 2sectan + tan^2
sec^2 + 2sectan + sec^2 - 1
What's the problem?

 

[Mess]

Similar to the question above that one, you'd simply have to expand ( sec + tan ) ^2
sec^2 + 2sectan + tan^2
sec^2 + 2sectan + sec^2 - 1
What's the problem?

Thank you so much.........I had not link that part with the question above. Thank you. <3 ^^

 

[waleedsmz]

Thank you so much.........I had not link that part with the question above. Thank you. <3 ^^

You're welcome. : )

 

[Fatima18]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w11_qp_12.pdf
Guys, number 7 ii and 8ii pls. Thanx!..

 

[waleedsmz]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_12.pdf

Guys, number 7 ii and 8ii pls. Thanx!..

As for 7ii)
You have the derivative of the equation, also known as "y dash". To get the original curve you simply need to integrate. So...
5 becomes 5x and -8/x^2 becomes +8/x. However, there is the constant of integration, so the final thing is. y = 5x + 8/x + c.
Point P is on the curve thus it satisfies the curve's equation. Substitute with its coordinates to find c.

As for 8ii)
First you find the intersections with the x-axis ( By putting y = 0 ). Those will be the limits of integration. The volume needed has a specific formula which is PI *int(y^2 dx)
y^2 = 8x - x^2
int ( 8x - x^2 dx ) = 4x^2 - x^3 / 3
Substitute with the limits and don't forget to multiply by PI.

 

[Fatima18]

As for 7ii)
You have the derivative of the equation, also known as "y dash". To get the original curve you simply need to integrate. So...
5 becomes 5x and -8/x^2 becomes +8/x. However, there is the constant of integration, so the final thing is. y = 5x + 8/x + c.
Point P is on the curve thus it satisfies the curve's equation. Substitute with its coordinates to find c.

As for 8ii)
First you find the intersections with the x-axis ( By putting y = 0 ). Those will be the limits of integration. The volume needed has a specific formula which is PI *int(y^2 dx)
y^2 = 8x - x^2
int ( 8x - x^2 dx ) = 4x^2 - x^3 / 3
Substitute with the limits and don't forget to multiply by PI.

Thanx a lot! ...However , I didn't understand something.The required volume is pi*y^2*dx....so before we integrate, dont we square the equation 8x -x^2????

 

[waleedsmz]

Thanx a lot! ...However , I didn't understand something.The required volume is pi*y^2*dx....so before we integrate, dont we square the equation 8x -x^2????

The equation itself is root(8x-x^2) so when it is squared, the root is just omitted and that's it.

 

[A star]

are all of you NOVEMBER candidates?

 

[Fatima18]

are all of you NOVEMBER candidates?

I em nd u?

 

[A star]

I em nd u?

hmm i am thinking of giving maths p3 and m1 in NOV but still tired from June exams :/

 

[Fatima18]

The equation itself is root(8x-x^2) so when it is squared, the root is just omitted and that's it.

Thanx a lot! ..
btw..cn u solve 10 ii?

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w12_qp_12.pdf

 

[Fatima18]

hmm i am thinking of giving maths p3 and m1 in NOV but still tired from June exams :/

Oh i c..which subjects did u give in may???How ws it?

 

[A star]

Oh i c..which subjects did u give in may???How ws it?

All good except maths p1 :/

 

[Fatima18]

All good except maths p1 :/

Tsk..em also scared for that....p1 ans s1..did u give s1?

 

[A star]

Tsk..em also scared for that....p1 ans s1..did u give s1?

yeah :/ but i messed up

 

[Fatima18]

yeah :/ but i messed up

uh oh...dats so disappointing...When did u finish your syllabus and when did u start practicing past papers?

 

[waleedsmz]

Thanx a lot! ..

btw..cn u solve 10 ii?
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w12_qp_12.pdf

Second part of the question is pretty easy, you just substitute with 2 in the given equation.

You find minimum/maximum of something by differentiating it, and equating the derived formula to zero. Thus to find the minimum of the GRADIENT you need to differentiate dy/dx. This would be 1-8/x^3 and this would be equal to zero when x = 2 . So how do we decide if it's a minimum or a maximum?

There are various ways, one of them would be substituting in the derived equation with a value smaller than 2 and a value greater than 2. If you do so with x =1 and 3 for example, you'd find that the derived formula changes from a negative(decreasing gradient) to a positive (increasing gradient) i.e. a minimum.

Another method would be simple substitution in the gradient equation. Since it's either a minimum or a maximum at x =2, compare the gradient with any value of x and that of 2 ( The second part of the question ), if the gradient of 2 is smaller then it must be a minimum, and that's the case given.

 

[Iffat]

I need help ppl...
2007 may-jun p1 q11 (i),(ii)n (iii)
for (i) i jus wanna kno the part that says how do u kno its a decreasing function and for(ii) i jus wanna kno how to find the domain
thanx in advance