Mathematics: Post your doubts here!

[Fatima18]

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.

Thanx!

 

[HongYue]

Can anyone help me with this http://papers.xtremepapers.com/CIE/...AS Level/Mathematics (9709)/9709_w06_qp_3.pdf Question 7 (ii) working pls. Thanks

 

[Iffat]

Can sum1 plz help with the foll questions:
2007 oct-nov p1 q4(ii),(iii)
2008 oct-nov p1 q2, q9(iii)
plz plz help me
thanx in advance

 

[Igcse stuff]

can someone help me with this question;

- Functions f and g are defined by

f(x)=4x-2k ...... g(x)= 9/(2-x)

(i) find the values of k for which the equation fg(x)=x has two roots
(ii) determine the roots of the equation fg(x)=x for the values of k found in part (i)

the answers are: (i) k=5 or k=-7
(ii) x=-4 or x=8

 

[Mess]

can someone help me with this question;

- Functions f and g are defined by

f(x)=4x-2k ...... g(x)= 9/(2-x)

(i) find the values of k for which the equation fg(x)=x has two roots
(ii) determine the roots of the equation fg(x)=x for the values of k found in part (i)

the answers are: (i) k=5 or k=-7
(ii) x=-4 or x=8

i) you have to solve them simultaneously and then use (b^2 - 4ac) > 0

ii)replace the values of k and form the composite function of fg(x) and equate it to x. Solve for x. You will get the answers

 

[Igcse stuff]

i) you have to solve them simultaneously and then use (b^2 - 4ac) > 0

ii)replace the values of k and form the composite function of fg(x) and equate it to x. Solve for x. You will get the answers

thanks alot mess

 

[Igcse stuff]

i) you have to solve them simultaneously and then use (b^2 - 4ac) > 0

ii)replace the values of k and form the composite function of fg(x) and equate it to x. Solve for x. You will get the answers

thanks alot mess

 

[Igcse stuff]

can someone help explain how to find the volume in Q 10(iii) and also help explain how y^2=1+2x becomes x=1/2(y^2-1) http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_11.pdf

 

[Acy Ijan]

SALAAM BHAIJAAN. PLEASE HELP ME FOR PART (iii). pLEASE.​

One turn of a game is as follows. Two coins are tossed. If the exposed faces of the two coins are the same as each other, then BOTH are tossed for a second time and the turn ends. Otherwise, the turn ends after the first toss of the coin. The scores, X obtained in the turn, is equal to the total number of HEADS exposed during that turn.

(i) I have already constructed the prob. distribution of X. P(X=3)=1/8 and P(X=1)=5/8.
(ii) Already calculated. E(X)=1.5 Var(X)=1
(iii) The scores obtained two randomly chosen turns are X1 and X2. E(X1 - X2)=0. PLEASE HELP ME IN FINDING OUT P(X1=X2).​

 

[Acy Ijan]

Assalamoalaikum Bhaijaan. If ever I'm stuck with some messy Mechanics Questions....will you help mee????

 

[Umar Zain]

Can someone give me the full solution for these?
9709/03/O/N/04 - Question 2
9709/03/M/J/08 - Question 2

 

[princess787]

hey! i need help in stats! Nov 2012 variant 1 p6! question.. i cant do the i) i understood evrything in the MS but from where do they -1.036! pls help! im badly stuck! THANX! here's the link to the paper: http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w12_qp_61.pdf
and d MS: http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w12_ms_61.pdf

 

[Nabeel.Ahmad]

Maths is Easy.

 

[deane26]

hey guys i need some help... how to do qns 4 NOV/12/33??

 

[Pradeep Adhikari]

http://www.freeexampapers.com/index...A Level/Maths/CIE/2010 Nov/9709_w10_qp_11.pdf

1.First question: mean and std. deviation...
Guys, i don't know how to do this type of questions...
So, please i would appreciate you a lot if you provide a step-wise solution for this question clearly....Thank you!

 

[Minato112]

hey guys i need some help... how to do qns 4 NOV/12/33??

Post a link please to facilitate the way of others. Thanks

 

[Minato112]

can someone help explain how to find the volume in Q 10(iii) and also help explain how y^2=1+2x becomes x=1/2(y^2-1) http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_11.pdf

Since it asks to find the volume about the y-axis, u have to make the equation of the curve becomes in terms of y.

y^2=1+2x
2x = y^2 - 1
x = (y^2 - 1)/2

Now U use the formula to find the volume :

*pie* *integration* [(y^2 - 1)/2]^2 from 0 to (y-coordinate of B)

You should get the answer. Hope it helps.

 

[Minato112]

Assalamoalaikum Bhaijaan. If ever I'm stuck with some messy Mechanics Questions....will you help mee????

Why was this thread created then?

 

[yuliana95]

Hi... I am learning Pure Maths 2&3 now, chapter 19(Differential Eqn). I have this question I can't seem to get it right:
Find the general solution of the differential equations:
(a) 4+x(dy/dx)=y^2

The answer key says that:
y=2(1-kx^4)/(1+kx^4) while my answer is y=2(1+kx^4)/(1-kx^4)

Please tell me what is wrong.. Any help is appreciated

 

[ni2005]

assalamualaikum!! can u please help me with this?
given the differential equation:
dH/dt = (100-H)^3
solve the differential equation, given tht H=101 when t=0, giving H in terms of t.

my answer is: H= 100+ (1/(2t+1)^0.5), i've taken negative square root, becasue then when t=0, H=101, but the answer in the marking scheme is H= 100- (1/(2t+1)^0.5), wheret=0 will give H=99.
jazaakallah