Mathematics: Post your doubts here!

[Scafalon40]

Okay i have the answering, but i dont know Q9 (i) if u can explain plzz.

so Q9 (iii)

If u got the a b values, 3 and 2

u sub them in the components.

3-λ = 4 + aµ
-2+2λ= 4 + bµ
1+λ = 2 - µ

so u get
3-λ = 4 + 3µ
-2+2λ= 4 + 2µ
1+λ = 2 - µ

choose any two and solve simultaneously

and u get µ = -1

no need to find λ or vice versa

take the value u got, i my case µ = -1
into its line equation and you willget
the i j k values.

about Q10 sorry i just saw it, will look into it, EDIT: i looked into it, i need to solve full question in order to answer tomorrow In Sha Allah

Thanks dude!
I'll wait for Q10
About Q9 (i):
set up the three equations:
3-t=4+q(a)
-2+2t=4+q(b)
1+t=2-q

t stands for lamda and q stands for 'mu'

Tidy up the equatins:
q(a)+t=-1..............................(1)
q(b)-2t=-6..............................(2)
q+t=1......................................(3)

now take the third equation and write it as t=1-q and substitute it in (1) and (2)

you'll get something like
qa+(1-q)=-1
qb-2(1-q)=-6

Now comes the part I won't solve XD
rearrange the equations to make q the subject and then equate them
et voila! you have your desired equation 2a-b=4!

EDIT: I'm so sorry dude I should've given you the heads up: the question is worth only one mark!
I just figured it out though: we have the values of a and b and we have those two equations with q as the subject. Just put a in the first one and you'll get q! Then use q for the point.
Sorry I wasted your time

 

[Yousif Mukkhtar]

Can some explain this Permutation question q5 a) ii)
http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w09_qp_61.pdf

Why is it 1 x 6 ^ 3?

 

[syed1995]

Can some explain this Permutation question q5 a) ii)
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w09_qp_61.pdf

Why is it 1 x 6 ^ 3?

This is not technically a permutation question since it won't require the P...

5000 and 6000 .. meaning it's a four digit number which starts with a 5.

so first number is 5.. that's a given.

5 _ _ _

Now since repetition is allowed..

the next 3 numbers can be anything from 1,2,3,4,5,6

meaning it can be 5555 5432 or 5646 .. all are possible.

so 6 choices for all the 3 other spaces..

meaning it becomes

1 * 6 * 6 * 6... = 1*6^3

 

[applepie1996]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w06_qp_3.pdf
question 7 part 4
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w05_qp_3.pdf
question 7 part 3
http://papers.xtremepapers.com/CIE/...AS Level/Mathematics (9709)/9709_w04_qp_3.pdf
question 9 part 3
PhyZac Rutzaba or anyone else

 

[daredevil]

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

plz help me with question 11.
what approach can we apply to this question.... i have gone totally blank on this one

 

[iKhaled]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w12_qp_12.pdf

plz help me with question 11.
what approach can we apply to this question.... i have gone totally blank on this one

this question is a nightmare to me..came in my exam and i ran out of time thinkin of it and it turned out to be a pretty stupid tricky question -_-

 

[minie23]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w12_qp_12.pdf

plz help me with question 11.
what approach can we apply to this question.... i have gone totally blank on this one

(i) Transform OCR in a right-angled triangle.
Thus, you will CR = x cm , OC = 20 - x cm
The angle (q) COR will be 0.6 rads.

we have hypotenuse and opposite, we use, sin q = CR/OC
= sin(06) = x/(20-x)

I guess, you can proceed now !

 

[ElvinJc]

Can someone please explain Q2 part i & Q8 PART i to me? Please!
http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w09_qp_32.pdf
THX

 

[Yousif Mukkhtar]

This is not technically a permutation question since it won't require the P...

5000 and 6000 .. meaning it's a four digit number which starts with a 5.

so first number is 5.. that's a given.

5 _ _ _

Now since repetition is allowed..

the next 3 numbers can be anything from 1,2,3,4,5,6

meaning it can be 5555 5432 or 5646 .. all are possible.

so 6 choices for all the 3 other spaces..

meaning it becomes

1 * 6 * 6 * 6... = 1*6^3

Thanks

 

[iKhaled]

hey..i need help with the last part of question 10 (b) i know how to sketch it and shade it but i cant find the max arg of z

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w11_qp_32.pdf

 

[PhyZac]

Thanks dude!
I'll wait for Q10
About Q9 (i):

.............................
Now comes the part I won't solve XD
rearrange the equations to make q the subject and then equate them
et voila! you have your desired equation 2a-b=4!

EDIT: I'm so sorry dude I should've given you the heads up: the question is worth only one mark!
I just figured it out though: we have the values of a and b and we have those two equations with q as the subject. Just put a in the first one and you'll get q! Then use q for the point.
Sorry I wasted your time

Thank you sooooooooooooooo much for the Help, Jazaka Allah khairan!! May Allah S.W.T bless you with high grades Ameeen, and May Allah S.W.T have mercy on you and your family.
Okay to get the value answer Q10 U need to make sure u have done part b correctly..
it is in short, a circle in forth quadrant, and there is a line 1/4 pi below x axis and a line 1

Now in the sketch below. You see, the largest point is in purple point. And to find it first we find the length of blue line under the green lines, to this use pythagoras theorem , so the short blue line is √2^2 +2^2 = 2√ 2
now to find the blue line till the purple point add a radius , which is 2, 2+2√2
now to find the largest Real Number, we have to find the value of xaxis above the purple point,
we know the angle is 1/4pi
so cos (1/4pi) = adj/ 2+2√2
adj = 2+√2

 

[Scafalon40]

Thank you sooooooooooooooo much for the Help, Jazaka Allah khairan!! May Allah S.W.T bless you with high grades Ameeen, and May Allah S.W.T have mercy on you and your family.
Okay to get the value answer Q10 U need to make sure u have done part b correctly..
it is in short, a circle in forth quadrant, and there is a line 1/4 pi below x axis and a line 1

Now in the sketch below. You see, the largest point is in purple point. And to find it first we find the length of blue line under the green lines, to this use pythagoras theorem , so the short blue line is √2^2 +2^2 = 2√ 2
now to find the blue line till the purple point add a radius , which is 2, 2+2√2
now to find the largest Real Number, we have to find the value of xaxis above the purple point,
we know the angle is 1/4pi
so cos (1/4pi) = adj/ 2+2√2
adj = 2+√2

Yeah I just got it! I just realised that I took 90 degrees to mean pi instead of 1/2pi
Thanks man, I appreciate it
And neat username: phyzac (fy-zc) rhymes with Issac (as in Newton). Cool

 

[PhyZac]

Can someone please explain Q2 part i & Q8 PART i to me? Please!
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w09_qp_32.pdf
THX

For question 2,

Well see for this, i got 3 and 4 (as in Mark Scheme) the way i understood the question was like, see, they need to find where is root, and find 2 consecutive (after each other) value of x, the only way is to try numbers in the equation, i tried 2 a -ve came, i tried 3 a -ve came, i tired 4 a +ve came, so this indicate a root lies between 3 and 4 (due to change in sign)

 

[Alice123]

Post your Mathematics doubts in this thread rosogolla993

 

[PhyZac]

hey..i need help with the last part of question 10 (b) i know how to sketch it and shade it but i cant find the max arg of z

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_32.pdf

See..the blue line is 3 ( to the centre)
and the purple line is 2 (the radius)
now the green line has the max arg, and makes 90 degrees with the radius
therefore
cos (x) = opp / hyp
sin x = 2/3
x = 0.729...
now add 1/2pi ( that is 90 degree)
u get 2.30

 

[applepie1996]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w06_qp_3.pdf
question 7 part 4
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w05_qp_3.pdf
question 7 part 3
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w04_qp_3.pdf
question 9 part 3
http://papers.xtremepapers.com/CIE/...AS Level/Mathematics (9709)/9709_w04_qp_3.pdf
question 10 please please solve it somebody !
PhyZac Rutzaba or anyone else

 

[trgirl]

hi everyone i have a question and i cannot find it can you explain how to solve this question??? :'(

"the mean of a certain normally distributed variable is 4 times the standard deviation. the probability that a randomly chosen value is greater than 5 is 0.15
find the mean and standard deviation????? but how????? i really do not understand mark scheme it says that z=1.036. but how?? where did it come from??? if you find it i will be sooooo happpy thanx in advance

 

[trgirl]

i

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w06_qp_3.pdf
question 7 part 4
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w05_qp_3.pdf
question 7 part 3
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w04_qp_3.pdf
question 9 part 3
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w04_qp_3.pdf
question 10 please please solve it somebody !
PhyZac Rutzaba or anyone else

have the same quetions as well :'(

 

[syed1995]

(i) Transform OCR in a right-angled triangle.
Thus, you will CR = x cm , OC = 20 - x cm
The angle (q) COR will be 0.6 rads.

we have hypotenuse and opposite, we use, sin q = CR/OC
= sin(06) = x/(20-x)

I guess, you can proceed now !

So Many O Level concepts recalled in just one post

 

[syed1995]

hi everyone i have a question and i cannot find it can you explain how to solve this question??? :'(

"the mean of a certain normally distributed variable is 4 times the standard deviation. the probability that a randomly chosen value is greater than 5 is 0.15
find the mean and standard deviation????? but how????? i really do not understand mark scheme it says that z=1.036. but how?? where did it come from??? if you find it i will be sooooo happpy thanx in advance

Always link the paper. So helping you is easier.

We need to take Phi Inverse of 0.15

P(X>5) = 0.15
P(z<-(5-4s)s) = -Phi^-1(1-0.15)
-(5-4s)/s = -Phi^-1(0.85)
-5+4s = -1.036s
5= 5.036s
s = 0.993


s = 0.993
mean = 4s
mean = 3.97