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Mathematics: Post your doubts here!

Prakhar

Prakhar

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yuliana95

yuliana95

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ZainH said:
Pretty simple question from mechanics.
A lift bringing miners to the surface of a mine shaft is moving with an acceleration of 1.2 m.s-2 . The total mass of the cage and the miners is 1600kg. Find the tension in the cable.

For some reason I'm getting 17920, where as the answer is 17900. Ugh, help please .___.
Click to expand...
I think your answer is correct, its just they make it into 3 significant figures.. hope it helps..:)
 
snowbrood

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i dont know how my friend solved this question the solution is below that question can anyone tell me as to how he got that angle 97.1 degrees
 

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D

darknessinme

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iKhaled said:
hello i need help with this question !! so annoying..
http://papers.xtremepapers.com/CIE/...AS Level/Mathematics (9709)/9709_w06_qp_3.pdf
question 7(ii)..how do we solve 2 equations with 3 unknowns Oo if we have these 2 equations a+2b+c = 0 and a-2b+c = 0
pleeaasee do help me !
Click to expand...

You can't solve such an equation.

If you use the vector product method, you can calculate the normal of the second plane because it's perpendicular to both the direction vector of line l and normal of plane 1. It's easier to visualise this if you draw it onto paper.
 
snowbrood

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~`Heba`~ :) said:
Mechanics question!
A car of mass 1000 kg moves along a horizontal straight road with its engine working at a contant rate of 25 KW. Assuming the work done by the car's engine is equal to kinetic energy generated, find the time taken to reach a speed of 30m/s.
The actual time taken is 31.6s and the car travels a distance of 680m in this time. Assuming there's an air resistance of magnitude R newtons,
(I) find the value of R.
(ii) the acceleration of the car when it's speed reaches 30m/s.
Please help :( thanks :D
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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
 
SalmanPakRocks

SalmanPakRocks

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sma786 said:
Mj 2007. Paper 01..
Question 3.. Prove the identity
...
Help plzz
Click to expand...
1-tan^2x/1+tan^2x

1-sin^2x/cos^2x * 1/1+sin^2x/cos^2x
LCM
cos^2x-sin^2x/cos^2x * 1 * cos^2x/cos^2x + sin^2x

cos^2x - sin^2x/cos^2x + sin^2x

cos^2x - sin^2x/1

1-sin^2x- sin^2x
1-2sin^2x
 
M

*MK*skydiver :D

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How can I solve this ?

z^5 -6z^3 +17z -10=0

Its answer probably contains a complex number ( Pure 3 -Complex numbers chapter )


And another question please ,
Z^4 + 16 =0


==> (z^2-4i )(z^2+4i)
==> (z^2+4i)(z-2root i ) (z+2root i )
==>z=+/-( 2root i ) or z=root(-4i) <<<<what can I do to this now ?
 
Binyamine

Binyamine

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unseen95 said:
how to integrate 1/(2x-1)ᶺ2
Click to expand...

Let y = 1/(2x-1)ᶺ2

it can be re written as y = (2x-1)ᶺ (-2)

Differentiating gives us = -2 * [(2x-1)ᶺ (-3)] * 2
= -4 [(2x-1)ᶺ (-3)]
= -4/[(2x-1)ᶺ3]

The way of doing it, is we are differentiating the function of a function which is of the form y = [ f(x) ] ^ n

we send the power down, we subtract 1 from the power and the we multiply by the derivative of the inside of the bracket i.e by the derivative of f(x)
 
A

aleezay

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abcde said:
Firstly, I apologise for the late reply. :/ You may not need this anymore, but this question is really interesting! :)

Lets say E is the expected time of reaching safety.
=> E = (1/3).2 + (1/3).(3+E) + (1/3).(5+E) (probability of 1st pick + probability of 2nd pick + probability of 3rd pick. E is added in 2nd and 3rd pick cuz the person is in the exact same scenario after travelling those 3 and 5 hours, respectively.)
=> E = [2+ (3+ E) + (5 + E)]/3
=> 3E = 2E + 10
=> E = 10.

So, it would take the person 10 hours (estimated).
Click to expand...
Thank you for your help :)
We did it this way, and we THINK we got it correct (since we came second)
Let the 3 doors be A ( leading to safety in 2hrs)
B ( bringing man back in 3hrs) n
C ( " " " 5hrs)

possible pathway - probability - time taken
1. A - (1/3) - 2hrs
2. B,A - (1/3).(1/3)= 1/9 - 5hrs
3. C,A - 1/9 - 7hrs
4. B,C,A or C,B,A - 1/27 - 10hrs


so expected time= one with max probability= 2hrs

What do you think?
 
abcde

abcde

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aleezay said:
Thank you for your help :)
We did it this way, and we THINK we got it correct (since we came second)
Let the 3 doors be A ( leading to safety in 2hrs)
B ( bringing man back in 3hrs) n
C ( " " " 5hrs)

possible pathway - probability - time taken
1. A - (1/3) - 2hrs
2. B,A - (1/3).(1/3)= 1/9 - 5hrs
3. C,A - 1/9 - 7hrs
4. B,C,A or C,B,A - 1/27 - 10hrs


so expected time= one with max probability= 2hrs

What do you think?
Click to expand...
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?
 
unseen95

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Binyamine said:
Let y = 1/(2x-1)ᶺ2

it can be re written as y = (2x-1)ᶺ (-2)

Differentiating gives us = -2 * [(2x-1)ᶺ (-3)] * 2
= -4 [(2x-1)ᶺ (-3)]
= -4/[(2x-1)ᶺ3]

The way of doing it, is we are differentiating the function of a function which is of the form y = [ f(x) ] ^ n

we send the power down, we subtract 1 from the power and the we multiply by the derivative of the inside of the bracket i.e by the derivative of f(x)
Click to expand...
hey i meant to integrate not differentiate.
 
Binyamine

Binyamine

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unseen95 said:
hey i meant to integrate not differentiate.
Click to expand...

Aie...You wanted to integrate and i explained how to differentiate.lol.

So we have to integrate 1/(2x-1)ᶺ2. we will re write it as (2x-1)ᶺ (-2)

When we integrate, we add one to the power, divide by the new power and divide by the derivative of the function.

= [( 2x - 1 ) ^ (-1 )] / [(-1) (2)]
= -1 / 2(2x -1 )
= -1/ (4x -2 )
or
= 1/ (2-4x)
 
yousef

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XPFMember said:
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
Click to expand...

can u please answer this question>>> give that expansion of (1+ax)^n begins 1+36x +576x^2... find "a" and "n">>>
 
C

chris123

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Hi,

Do u have alll the past papers for 2012? I can't find some 2012 on this site.
Also I need further maths (all modules including mechanics) and chemosytry and physics.

Thanks
 
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