Maths - Homework Help Thread

[al_islam]

Any problems with maths, just leave it in my PM box or on a REP.

If my deputy Adil Hussain cant answer, then I probably will be able to answer.

No one is doing anyones homework, but a little pointer in the right direction is on offer.

[MrOnline]

Bismillahirrahmanirraheem,

Assalamualaykum brothers/sisters,

Mashallah brother al_islam is offering a wonderful opportunity for the ummah to take advantage of. I have to say this brother is very gifted academically and he will always strive to achieve good for his fellow brothers/sisters. He gives his utmost help whenever needed, so brothers/sisters just post here (in this thread) whenever you have trouble solving any maths problems etc;
Alternatively, as al_islam suggested, you may PM him or leave him a rep. Whichever suits you as an individual.

Jazakullah!

Wassalam.

[MrOnline]

Bump.////////

[ana_mujahid]

will do brothers :)

[al_islam]

that way its in one place and others can see all problems solved as they might find it helpful too.....rather than 50 diff threads.....it makes sense to have one.

[al_islam]

QUESTION_
x= X(1)+X(2)+.........X(N)
______________________
n

how can i do this with calculator ?

Answer

Using brackets....its quiet simple.

you use the open and close bracket buttons and that allows you to do long calculations, but u need a 'scientific' calculator....a slightly more advanced one.

[Joha]

QUESTION_


Answer

Using brackets....its quiet simple.

you use the open and close bracket buttons and that allows you to do long calculations, but u need a 'scientific' calculator....a slightly more advanced one.

you sure he's not just asking how to calculate the mean using a calculator?

[al_islam]

you sure he's not just asking how to calculate the mean using a calculator?

I PM ed him to ask if he was happy with it and he said it was all he was after. Thanks for the input.

[Ibn Khattab]

brother what qualifications do you have? like upto what level can you provide help?

[al_islam]

brother what qualifications do you have? like upto what level can you provide help?

Bro, Dont ask such questions....If you need help ask me....other than that, thats all I have to say.

[Desi-Fly-Chick-]

ok..im sorry sister..please dnt ansa that question people...ill ask else where..tanx

[MrOnline]

brother what qualifications do you have? like upto what level can you provide help?

GCSE=me

[Al-Islam= a much higher level]

[MrOnline]

ok..im sorry sister..please dnt ansa that question people...ill ask else where..tanx

Al-Islam is a brother. :smack: By the way feel free to post any challenging maths questions/problems in this thread.

[al_islam]

Logarithms

Logarithms are simply a way of writing indices.

If a = bc then c = logba

Example:

We know that 10^2 = 100
Therefore, log10 100 = 2

You may often see ln x and log x written, with no base indicated. It is generally recognised that this is shorthand:

loge x = lnx

log10 x = lgx or logx (on calculators)

e is the exponential function, which is equal to 2.71828…

Laws of Logs

The properties of indices can be used to show that the following rules for logarithms hold:

loga x + loga y = loga (xy)

loga x – loga y = loga (x/y)

loga x^n = nloga x

FROM: http://www.mathsrevision.net/alevel/pages.php?page=24

[dhakiyya]

InshaAllah I'm doing A-level maths as homestudy soon :S does anyone know any good internet sites for doing A level maths, like study support, revision, practice and stuff?

[dhakiyya]

actually come to think of it a GCSE revision site would be in order too cause its waaaaaaaaayyy long time ago I did GCSE maths and I just skim read the above and I can't remember what a "surd" is :banghead: I just remember joking with my maths teacher about how "ubsurd" the lesson was lol.

[al_islam]

I listed a site for the 'Logs', that should have most other topics as well.

'Proof' is the hardest topic in maths.

The rest of maths is just playing around with numbers, and expressing something as another.......This thread may be all you need.

[MrOnline]

does anyone know any good internet sites for doing A level maths, like study support, revision, practice and stuff?

Yes. Click here http://www.ummah.com/forum/showthread.php?t=160038 :D

[MrOnline]

"ubsurd"

ABsurd? Is it not? :o

LOL regardless. :)

[dhakiyya]

I have no idea, I suck at spelling. so you're probably right lol. :up: thanks for the link... err except that I already know about this thread lol

[al_islam]

Surds are numbers left in "square root form" (or "cube root form" etc).

Addition and subtraction of surds
a√b + c√b = (a + c)√b
a√b - c√b = (a - c)√b

Examples
4√7 - 2√7 = 2√7.
5√2 + 8√2 = 13√2

NB1: 5√2 + 3√3 cannot be manipulated because the surds are different (one is √2 and one is √3).
NB2: √a + √b is not the same as √(a + b) .


Multiplication and Division
√ab = √a × √b
√(a/b) = √a/√b

Examples
√5 × √15 = √75
= √25 × √3
= 5√3.

(1 + √3) × (2 - √8) [The brackets are expanded as usual]
= 2 - √8 + 2√3 - √24
= 2 - 2√2 + 2√3 - 2√6


Rationalising the denominator
It is untidy to have a fraction which has a surd denominator. This can be "tidied up" by multiplying the top and bottom of the fraction by a surd. This is known as rationalising the denominator, since surds are irrational numbers and so you are changing the denominator from an irrational to a rational number.

Example
Rationalise the denominator of:
a) 1
√2 .

b) 1 + 2
1 - √2

a) Multiply the top and bottom of the fraction by √2. The top will become √2 and the bottom will become 2 (√2 times √2 = 2).

b) In situations like this, look at the bottom of the fraction (the denominator) and change the sign (in this case change the minus into plus). Doing this forms the conjugate of the denominator. Now multiply the top and bottom of the fraction by this.

Therefore:
1 + 2 = (1 + 2)(1 + √2) = 1 + √2 + 2 + 2√2 = 3 + 3√2
1 - √2 (1 - √2)(1 + √2) 1 + √2 - √2 - 2 - 1

= -3(1 + √2)

SOURCE: http://www.mathsrevision.net/alevel/pages.php?page=40

[MrOnline]

Solve the simultaneous equation.

y = x + 7
x2 + y2 = 25

Please show your working. I'm generally quite good with simultaneous equations but this is a weird one and i really want to know how to figure this one out.

[Ibn Al-Jarrah]

Solve the simultaneous equation.

y = x + 7
x2 + y2 = 25

Please show your working. I'm generally quite good with simultaneous equations but this is a weird one and i really want to know how to figure this one out.

sub in y = x + 7
x^2 + (x + 7)^2 = 25 (x^2 means x squared)

x^2 + [x^2 + 14x + 49] = 25

2x^2 + 14x + 24 = 0 (take 25 to the other side)

(2x+ 8 )(x+ 3) = 0 (factorise)

x = -3, x = -4

[MrOnline]

sub in y = x + 7
x^2 + (x + 7)^2 = 25 (x^2 means x squared)

x^2 + [x^2 + 14x + 49] = 25

2x^2 + 14x + 24 = 0 (take 25 to the other side)

(2x+ 8 )(x+ 3) = 0 (factorise)

x = -3, x = -4

Jazakullah! ...To you and to al-islam (for helping me on msn). You've helped me with a 7 mark question. Surely you both deserve some REPs. I'll add them on now.

[al_islam]

sub
2x^2 + 14x + 24 = 0 (take 25 to the other side)


Ye here though I would divide by 2 so you get:

x^2 + 7x + 12 = 0

And then its easier to factorise.

Both ways are correct, though.

[MrOnline]

Ye here though I would divide by 2 so you get:

x^2 + 7x + 12 = 0

And then its easier to factorise.

Both ways are correct, though.

Jazakullah. We've already gone through this on msn. :up: Rep 4 U

[Ibn Al-Jarrah]

Ye here though I would divide by 2 so you get:

x^2 + 7x + 12 = 0

And then its easier to factorise.

Both ways are correct, though.

:smack:spent ages tryna factorise it.

edit: no need for the rep bro!:DJazakallah khayr anyways

[al_islam]

:smack:spent ages tryna factorise it.

edit: no need for the rep bro!:DJazakallah khayr anyways

Well bro,

If you need to polish on your maths, you know where I am :up:

[MrOnline]

Al-Islam banned? :(

[MrOnline]

the length of time, t (seconds) of her favourite tracks is given in the table.

Time (sec) Frequency
120 (less than or equal to) t (less than) 150 12
150 (less than or equal to) t (less than) 180 17
180 (less than or equal to) t (less than) 210 21
210 (less than or equal to) t (less than) 240 8
240 (less than or equal to) t (less than) 270 2


Calculate estimates of the mean and standard deviaion of these times.

[MrOnline]

With reference to the above question...how does the answer booklet suggest you do 10830 / 60 to work out the mean? :confused:

I know we're we've got the 60 from but what about the 10830?

[MrOnline]

I've got it! Mid value X frequency (then total it all up)

[al_islam]

Question:


I need to do a 3x3 cube that has the numbers 1-9 and each column and row (as well as diagonally) must add up to 15.

Can you do it?!

Answer:

Many ways to do it.

Main numbers you need are in bold, then you can work around the rest:

2 7 6
9 5 1
4 3 8

[Ibn Al-Jarrah]

Question:



Answer:

Many ways to do it.

Main numbers you need are in bold, then you can work around the rest:

2 7 6
9 5 1
4 3 8

:S dont get what this is about. 3x3 cube?:rubeyes:

[al_islam]

With reference to the above question...how does the answer booklet suggest you do 10830 / 60 to work out the mean? :confused:

I know we're we've got the 60 from but what about the 10830?

Bro all your doing is plugging numbers into formulae.

You need the formulae for Mean and Standard Deviation.

HINT:

The formula for the mean for a frequency is different to a normal mean.

So use the formula for the Mean for the Frequency...(group tables)

[truemuslima]

lol u do ppls homework-- i mean HELP them wit homework...

i need tons of help but its sorta stupid coz yu ppl all in waaay up der and i is waaaay down in high school.. getin college credit tho..hehe
i hate algebra.
i hate geometry.
i hate- ok fine i hate all math stuff . but they are easy, just not fun to do. of course.
anyway.
plz dont make fun of da "baby" questions i got . my teacher sucks at explaining how to do dem, he just sits there and does the problem then asks evryone got it? and i say u havent explained how u even got da answer, and he tries to do it again, and does the same thing, then he asks evryone gottit, i go, forget it i juss find som online help or somthin. and he still tryna explain... i fink he need to b fired. he a mean and dum teacher. anyway here is just one question

Find the value: C(8, 4)

easy fo u so plz dont say nutin to mak me mess somone up .kk
Jazakallah khair

Wassalam

[Ibn Al-Jarrah]

Find the value: C(8, 4)

easy fo u so plz dont say nutin to mak me mess somone up .kk
Jazakallah khair

Wassalam

what topic is this:S whats the C about?

[al_islam]

I think she is on about finding mid-points of lines.

The C represents the points to be used for the line and the co-ordinates for it are given in the brackets.

Use the formulae for finding the straight line in a graph (y=mx + c).....

not much more to it...

[truemuslima]

oi ssorry i forgot that part. i just copy pasted it off the test and forgot to mention wat its bout.
its that combination permutation stuff. i kno tha permutation alone is easy of course but da teachre nevr said nutin bout this then put it on the test.
Jazakallah khair
Wassalam

[Ibn Al-Jarrah]

oi ssorry i forgot that part. i just copy pasted it off the test and forgot to mention wat its bout.
its that combination permutation stuff. i kno tha permutation alone is easy of course but da teachre nevr said nutin bout this then put it on the test.
Jazakallah khair
Wassalam

:SYou mean like 8C4? thats using the formula n!/[r!(n-r!)] where n is the first number and r is the second one right? Or u could use a calculator

by the way ! is factorial, which im sure u know means x(x-1)(x-2)(x-3)...until u reach one

so 8C4 would be:

(out of 8 possibilities, Choose 4, how many different arrangements are there?)

8x7x6x5x4x3x2x1
4x3x2x1(4x3x2x1)

You can cancel that to:

8x7x6x5
4x3x2x1

or 1680 / 24 = 70

so choosing 4 possibilities out of 8, there are 70 different ways u can do it e.g. choosing 4 counters from 8 different coloured counters, there are 70 different arrangements of coloured counters you could make

btw all that is without a calculator, and i dont think u need to know the formula until A level. Im assuming thats what u meant tho?

[truemuslima]

oooooh i get it. sorry for confusin.
Jazakallah khair bro

[al_islam]

On a calculator you have an (!) button and it does it all for you if you type in:

8(!)4,

Permeations theory is not that difficult.

[Ibn Al-Jarrah]

On a calculator you have an (!) button and it does it all for you if you type in:

8(!)4,

Permeations theory is not that difficult.

There is actually a C button on the calculator which u use e.g. 8C4. The factorial (!) is for when u r using the formula. 8!4 would give the wrong answer bro

[al_islam]

There is actually a C button on the calculator which u use e.g. 8C4. The factorial (!) is for when u r using the formula. 8!4 would give the wrong answer bro

Glad to see someone else is on the ball.

I was just testing you.:rolleyes:

[Ibn Al-Jarrah]

Glad to see someone else is on the ball.

I was just testing you.:rolleyes:

lol of course:D

[Smiles With Joy]

Ye here though I would divide by 2 so you get:

x^2 + 7x + 12 = 0

And then its easier to factorise.

Both ways are correct, though.

only as long as you rememebr to include the factor of 2 prior to the factorisation; admittedly this si more if the questions asks for factorising, but it is still important.

And re the C and P buttons; usually you see a button labelled nPr as well as one labelled nCr; make sure you use the correct one - usually its just nCr