• We need your support!

    We are currently struggling to cover the operational costs of Xtremepapers, as a result we might have to shut this website down. Please donate if we have helped you and help make a difference in other students' lives!
    Click here to Donate Now (View Announcement)

Mathematics: Post your doubts here!

Esme

Esme

Messages
681
Reaction score
438
Points
73
TaffsAsLevel said:
Will we get full marks if we got our final answer correct but very short working? It is 6 marks but I got correct? Or you have to do the long way? Like if Find length AB given the line r=something and meets at plane p at A and plane q at B. Find AB length (June 2010 paper 32)
Click to expand...

It's better you show all the steps for whichever method you choose. Because with vectors there's always more than one way to obtain answer. You can do whatever way seems easy or short to you but show how you've done it.
 
Esme

Esme

Messages
681
Reaction score
438
Points
73
AlishaK

AlishaK

Messages
345
Reaction score
394
Points
63
Esme said:
Here's what i've done:

argu = arg( (1+2i)/(1-3i) )
argu = arg(1+2i) - arg(1-3i)
arg(-1/2 + i/2) = tan^-1(2) - tan^-1(-3)
tan^-1(-1) = tan^-1(2) + tan^(3)
3π/4 = tan^-1(2) + tan^-1(3)

Hope you got it :)
Click to expand...
yup i did that, in a pretty messy way thou. lol ... Thanku thanku! :)
 
Esme

Esme

Messages
681
Reaction score
438
Points
73
Soldier313 said:
Aoa wr wb
Can someone please help me, for qn 10 ii of this paper, while integrating, i don't get where the -ve sign comes before the 3/2
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s07_qp_3.pdf
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s07_ms_3.pdf
Thank you :)
Click to expand...

Wa laikum as salaam :)

S denotes integration

S (9-h)^-1/3
Now to integrate this you multiply by 3/2 and divide by -1. This gives -3/2
If you're wondering why we divide by -1, it's the coefficient of h. And when we integrate we divide by the coefficient of the variable.
 
Soldier313

Soldier313

Messages
960
Reaction score
3,500
Points
253
Esme said:
Wa laikum as salaam :)

S denotes integration

S (9-h)^-1/3
Now to integrate this you multiply by 3/2 and divide by -1. This gives -3/2
If you're wondering why we divide by -1, it's the coefficient of h. And when we integrate we divide by the coefficient of the variable.
Click to expand...
oh right! Thank you so much for that :)
 
AlishaK

AlishaK

Messages
345
Reaction score
394
Points
63
Esme said:
Wa laikum as salaam :)

S denotes integration

S (9-h)^-1/3
Now to integrate this you multiply by 3/2 and divide by -1. This gives -3/2
If you're wondering why we divide by -1, it's the coefficient of h. And when we integrate we divide by the coefficient of the variable.
Click to expand...
why do we divide by 3/2 ? i hope i dont sound dumb?! :oops:
 
Esme

Esme

Messages
681
Reaction score
438
Points
73
AlishaK said:
why do we divide by 3/2 ? i hope i dont sound dumb?! :oops:
Click to expand...

Lol no you don't
Actually what you're doing is dividing by (n+1). In this case n=-1/3
n+1=2/3
So when you divide by 2/3, it is the same as multiplying by 3/2
 
AlishaK

AlishaK

Messages
345
Reaction score
394
Points
63
Esme said:
Lol no you don't
Actually what you're doing is dividing by (n+1). In this case n=-1/3
n+1=2/3
So when you divide by 2/3, it is the same as multiplying by 3/2
Click to expand...
OMG!!! i feel so dumbo! u know what i read (9-h)^-1 is divided by '3'...hahaha ! i know that thing thou...lol thanks anyway.... c
 
Esme

Esme

Messages
681
Reaction score
438
Points
73
mominzahid

mominzahid

Messages
134
Reaction score
17
Points
28
Esme

Esme

Messages
681
Reaction score
438
Points
73
mominzahid said:
Can someone please explain to me q10 (iii)... i've been stuck on it for a while now... please help guys :/
Also please explain q7(iii) and q8(i).. in q8(i) i keep getting -10 instead of just 10u.. Just explain that point where im making the mistake.. thanks alot :D
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s12_qp_32.pdf
Marking scheme: http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s12_ms_32.pdf
Click to expand...

Q7iii)

Esme said:
Here's what i've done:

argu = arg( (1+2i)/(1-3i) )
argu = arg(1+2i) - arg(1-3i)
arg(-1/2 + i/2) = tan^-1(2) - tan^-1(-3)
tan^-1(-1) = tan^-1(2) + tan^(3)
3π/4 = tan^-1(2) + tan^-1(3)

Hope you got it :)
Click to expand...
 
Esme

Esme

Messages
681
Reaction score
438
Points
73
mominzahid said:
Can someone please explain to me q10 (iii)... i've been stuck on it for a while now... please help guys :/
Also please explain q7(iii) and q8(i).. in q8(i) i keep getting -10 instead of just 10u.. Just explain that point where im making the mistake.. thanks alot :D
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s12_qp_32.pdf
Marking scheme: http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s12_ms_32.pdf
Click to expand...

As for Q8i) you're getting -10. that's correct. now you have to change signs because the limits have been exchanged. If you notice the limits are supposed to be (6-5)^1/2 and (6-2)^1/2
1 being your upper limit and 2 being the lower limit. However the question asks ask to write 2 as the upper limit and 1 as the lower limit. So when you exchange these limits you have to change the sign

Sounds a bit confusing but think about it, you'll get it
 
MustafaMotani

MustafaMotani

Messages
1,321
Reaction score
490
Points
93
Esme said:
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w12_qp_33.pdf
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w12_ms_33.pdf

Q7iii) In such cases where they haven't given the initial value for the iteration formula, we just assume it to be 0 ?
MustafaMotani Told ya, I'd annoy you :p

Also, in complex numbers what is the square root of i ?
Click to expand...

I dont know what sould be the initial value in such cases .. I think situation hints us what to take ...

square root of i = 1/root2 + i/root2
 
Esme

Esme

Messages
681
Reaction score
438
Points
73
MustafaMotani said:
I dont know what sould be the initial value in such cases .. I think situation hints us what to take ...

square root of i = 1/root2 + i/root2
Click to expand...

Well in this case, there isn't any hint. And I did get the answer by taking 0, but I'm not sure if that's right.

Is there any method to arrive at 1/root2 + i/root2 ? Or it's just something we should know? I'm not exactly able to solve root of i
 
MustafaMotani

MustafaMotani

Messages
1,321
Reaction score
490
Points
93
Esme said:
Well in this case, there isn't any hint. And I did get the answer by taking 0, but I'm not sure if that's right.

Is there any method to arrive at 1/root2 + i/root2 ? Or it's just something we should know? I'm not exactly able to solve root of i
Click to expand...

i^(1/2) = a + ib
i = (a + ib)^2
i = a^(2) + 2abi - b^(2)
a^(2) - b^(2) = 0 , 2ab = 1

solve them simultaneously
 
MustafaMotani

MustafaMotani

Messages
1,321
Reaction score
490
Points
93
Esme said:
Well in this case, there isn't any hint. And I did get the answer by taking 0, but I'm not sure if that's right.

Is there any method to arrive at 1/root2 + i/root2 ? Or it's just something we should know? I'm not exactly able to solve root of i
Click to expand...

may be then its okay.. but i cant guarantee it ..
 
You must log in or register to reply here.
Top