Mathematics: Post your doubts here!

[iKhaled]

Jazak Allah Khairan..thank you so much, May Allah reward you for the help ur providing other students with.

I fully understood the first part. Alhamdulilah. And your answer is exactly similar to markscheme

coming to the second part of the question..

t=1/4pi ..................i got it
m=1/2 ....................i got it

but in markscheme the equation seem different..... the "c"

here is a copy:
View attachment 20543

oh sorry i made such a stupid error

i calculated y as in sin (2t) not sin^2 t so i got the answer y=1 instead of y=1/2

did u get me ?

 

[Syed Mohammad Ali]

For the question x(x-2) < 5:
x^2 - 2x - 5 < 0

x^2 - 2x + 1 - 6 < 0
(x-1)^2 - 6 < 0
(x-1)^2 < 6
|x-1| < sqrt(6)
hence,
1-sqrt(6) < x < sqrt(6)+1

wat bout the first 1. BETWEEN! Thanks . May Allah bless you.

 

[aleezay]

I still think the expected time owuld be the sum of all probabilities like it always is. Your solution would be completely correct only if the maximum probabilty was 1 i.e. A was certain to happen so the expected time would definitely be 2 hours.
P.S. Which contest was this?

LUMS PsiFi This was a question from Math Gauge.

 

[abcde]

LUMS PsiFi This was a question from Math Gauge.

I knew it!

 

[Kandinsky]

Q : Find the values of k for which the equation k2X2 + 2kX +1 =0 have no roots.

In fact, it will not have roots only if k = 0.
Here is the explanation:

k^2 * x^2 + 2k*x + 1 = 0
(kx)^2 + 2*(kx) + 1 = 0
it seems like it is full square
(kx+1)^2 = 0
so, kx+1 = 0
this equation does not have roots if and only if k = 0;

 

[PhyZac]

oh sorry i made such a stupid error

i calculated y as in sin (2t) not sin^2 t so i got the answer y=1 instead of y=1/2

did u get me ?

oh yes..i got it..!!

Jazak Allah khairan..!!!! Thank you!

 

[Mayedah]

differentiate y=9/(2-x) ??

 

[PhyZac]

differentiate y=9/(2-x) ??

This will solve your problem
Click here

 

[Mayedah]

This will solve your problem
Click here

thanks
got it

 

[Chaitanya Agrawal]

Assalamoalaikum Wr Wb!

Post your doubts here. Make sure you give the link to the question paper when posting your doubts.


May Allah give us all success in this world as well as the HereAfter...Aameen!!

And oh yeah, let me put up some links for A level Maths Notes here.

Check this out! - Nice website, with video tutorials for everything! MUST CHECK

My P1 Notes! - Only few chapters available at the moment!

Maths Notes by destined007

Some Notes for P1 and P3 - shared by hamidali391

A LEVEL MATHS TOPIC WISE NOTES

MATHS A LEVEL LECTURES

compiled pastpapers p3 and p4 - by haseebriaz

Permutations and Combinations (my explanation)- P6

Permutations and Combinations - P6

Vectors - P3

Complex No. max/min IzI and arg(z) - P3

Sketcing Argand Diagrams - P3 (click to download..shared by ffaadyy)

Range of a function. - P1

do u know about oct/nov 2012 mark schemes and thresholds?

 

[Sadiqa Ali]

please sum1 help me out for these questions m/j 2012 paper 12
Q)1
Q)6 part ii,iii
Q)7 part b
Q)9

 

[Binyamine]

please sum1 help me out for these questions m/j 2012 paper 12
Q)1
Q)6 part ii,iii
Q)7 part b
Q)9

Here you are man ::http://www.youtube.com/playlist?list=PLOueJSLH9a-OSW0qHO8K8HzxgniUaU3Mp
Its on youtube. Click on the question you need.

 

[Alice123]

sin2thetadx/dtheta=(x+1)cos2theta
can ne1 help?

 

[Beca1206]

Hello,
Can Anyone pls help me with this question, i got one point as pi over 6 (30 degrees) but i cannot get the other point.

 

[~`Heba`~ :)]

can u please tell me the source of this question so that i could read from that source and compare the answers actually i get a different value for time taken

I got it from mechanics notes for dr.Nabeel Eliass if you know them

 

[french410]

Hello,
Can Anyone pls help me with this question, i got one point as pi over 6 (30 degrees) but i cannot get the other point.

dont u get sin x=0.5 : means x=30 degrees or 360-30=300 degrees




hope that helped

 

[french410]

sin2thetadx/dtheta=(x+1)cos2theta
can ne1 help?

the deravitive(dx/dϴ) of sin2ϴ is 2cos2ϴ. therefore 2cos2ϴ=(x+1)cos2ϴ
this means (x+1)=2 and thus x=1

hope that helped

 

[Iffat]

can sum1 plz help me asap
-Express 4x2-12x+3 in the form (ax+b)2+c where a, b and c are constants and a is greater than 0
-The line y=5x-3 is a tangent to the curve y=kx2-3x+5 at the point A. Find the cordinates of A

 

[Kandinsky]

the deravitive(dx/dϴ) of sin2ϴ is 2cos2ϴ. therefore 2cos2ϴ=(x+1)cos2ϴ
this means (x+1)=2 and thus x=1
hope that helped

I think the question is a differential equation.

sin2thetadx/dtheta=(x+1)cos2theta
can ne1 help?

so if sin2theta in your notation is sin(2*theta), not sin^2(theta), then

dx/ (x+1) = cot(2*theta) d(theta)
integrating both parts

ln|x+1| = 1/2* ln|sin(2*theta)| + C
x + 1 = sqrt(C* sin(2*theta))
and hence x = sqrt(C*sin(2theta)) - 1
Let us check by substitution:
suppose theta = a
dx/da = 2*C*cos(2a)/ (2* sqrt(C*sin(2a))) = sqrt(C)*cos(2a)/ sqrt(sin2a);

then, sin(2a)* dx/da = sqrt(C)* cos(2a) * sqrt(sin 2a) = cos(2a) * (x+1). It is true.

 

[SalmanPakRocks]

can sum1 plz help me asap
-Express 4x2-12x+3 in the form (ax+b)2+c where a, b and c are constants and a is greater than 0
-The line y=5x-3 is a tangent to the curve y=kx2-3x+5 at the point A. Find the cordinates of A

- 4[ x^2 - 3x + 3/4]
4 [ (x)^2 - 2(x)(3/2) + (3/2)^2 - (3/2)^ + 3/4]
4 [ (x-3/2)^2 - 9/4 + 3/4]
4(x-3/2)^2 -9 + 3
4(x-3/2)^2 -6