Mathematics: Post your doubts here!

[notnek01]

"find a formula for the sequence 5, 14, 29, 50, 77, ... Since you know that the sequence is quadratic, you are looking for an expression an^2 + bn + c for the n-th term. With n = 1 we have a + b + c = 5, with n = 2 we have 4a + 2b + c = 14, and with n = 3 we have 9a + 3b + c = 29."

How do u find the formula.. i mean what are the steps u do to find it..can u show how..cuz m not getting it.. :/

This method is not part of the IGCSE syllabus but it's useful to know:

Firstly, a is equal to the second difference divided by 2. The first differences are 9, 15, 21, 27, ... so the second difference is 6. This means that a = 6/2 = 3.

So the formula looks like 3n^2+bn+c.

Now you need to find b and c by substituting in some values:

n=1 : The 1st term is 5 so we have 3(1^2) + b(1) + c = 5 --> 3 + b + c = 5 --> b + c = 2
n=2: The 2nd term is 14 so we have 3(2^2) + b(2) + c = 14 --> 12 + 2b + c = 14 --> 2b + c = 2


Now solve these two simultaneous equations (subtract the equations) to find b and c and you get:

b=0, c=2

So the nth term is 3n^2 + 2

An IGCSE question would never ask you to find the nth term of 5, 14, 29, 50, 77, ... without any extra information.

 

[ZaqZainab]

This method is not part of the IGCSE syllabus but it's useful to know:

Firstly, a is equal to the second difference divided by 2. The first differences are 9, 15, 21, 27, ... so the second difference is 6. This means that a = 6/2 = 3.

So the formula looks like 3n^2+bn+c.

Now you need to find b and c by substituting in some values:

n=1 : The 1st term is 5 so we have 3(1^2) + b(1) + c = 5 --> 3 + b + c = 5 --> b + c = 2
n=2: The 2nd term is 14 so we have 3(2^2) + b(2) + c = 14 --> 12 + 2b + c = 14 --> 2b + c = 2


Now solve these two simultaneous equations (subtract the equations) to find b and c and you get:

b=0, c=2

So the nth term is 3n^2 + 2

An IGCSE question would never ask you to find the nth term of 5, 14, 29, 50, 77, ... without any extra information.

Can i use this equation like for any sequence?

 

[notnek01]

Can i use this equation like for any sequence?

This method will work for any quadratic sequence.

 

[kirstyhawke]

hey, do you have any other formulas for finding the nth term when there are uncommon differences?
I found: a+(n-1)d+0.5(n-1)(n-2)c

 

[Ahmed Nasser]

i want to know if theres any formulas for the nth term like the a+(n-1)d ??? because i'm really losing too much from the nth term question

 

[Rockzstar]

http://papers.xtremepapers.com/CIE/Cambridge%20IGCSE/Mathematics%20(0580)/0580_s11_qp_41.pdf

Please explain q)2 C

 

[Catherine7532]

plz can u help me with the mensuration question
jun 2007 paper4 Q7c

 

[lklk123]

HELP!! P43 MJ/12 Q3 Cii

 

[MARYAM aziz]

iv a problem in finding mean and median in statistics 0580/04 /m/j /07 Q 6 b and c

 

[ZaqZainab]

http://papers.xtremepapers.com/CIE/Cambridge%20IGCSE/Mathematics%20(0580)/0580_w07_qp_4.pdf what does vertices means int this question 5 c v
isn't vertices used in graphs and why is the answer so not in my brain and i can't relate it to the question Please help me out

 

[abdulrhaman munther]

Guys november 2012 "Q1 d(ii) ... Pleaaase help

 

[abdulrhaman munther]

Varaiant 1

 

[Ahmed Al Hilali]

http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Mathematics (0580)/0580_w09_qp_4.pdf

This is one of the hardest paper i solved , and i have a lot of Q ,, please help me ..

Q 2 a iv , why the factor is -1 but not 1 ?

Q3 C

Q6 D

Q7 C ii

Q8 C iii

Q10 C , f , g

Solve the one you know , plz help

 

[AlphaWolf]

When drawing a graph, how do you draw the curve properly without messing it up? The question have a value of 5 marks approx.

 

[AlphaWolf]

Are you allowed to draw it: connect-the-dots style. In my textbook one of the graphs is drawn that way. I have attached the picture below. When joining reciprocal graphs it is adifficult.

 

[saifeddin]

what is the formula for shear and stretch? for transformation

 

[Catherine7532]

for november 2009 q2 a iv since the y axis is the invariant line, you go backwards so u count it as -4( distance of object from invariant line)
(distance between object n image) is 4. so -4/4 gives u -1.

 

[Catherine7532]

shear= distance between object n image/distance of object from invariant line
stretch= distance of image 4rm invariant line/distance of object from invariant line

 

[saifeddin]

shear= distance between object n image/distance of object from invariant line
stretch= distance of image 4rm invariant line/distance of object from invariant line

thanks a lot

 

[anonimo786]

AsSalamoAlaikum Wr Wb...

Stuck somewhere in Maths?? Post your queries here! Members around will help you InshaAllah.

NOTE: If you have any doubt in the pastpper questions, then kindly post the link to the paper!

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

SEQUENCES-Points to remember:
Many people find it hard, but to be honest it's just more of logic..that's all!

Sequences!

Using log for indices.

Salams... Could u explain bearings and locus, plzz. May Allah reward your effort