# Help me with Maths, Please!

Discussion in 'Education & Careers' started by Idris16, Jun 13, 2012.

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### Idris16Junior Member

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salam alaykum warahmatullah wabarakatuh

a)

2x + y = 6
3x − y = 9

b)

2x + 3y = 16
3x + y = 10

c)

3x − 2y = 20
5x − 5y = 25

I hope anyone can show me the answers of x and y in simple ways. JazakAllah khayr.

Here are the answers actually, but I want help with how to work out the answers, what do I do to get the right answers:

a) x = 3 and y = 0

b) x = 2 and y = 4

c) x = 10 and y = 5
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### ilyas_ehUsed to be active here!

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1 question, why do you want to go by substitution approach?
unless it is specifically mentioned in the question don't go for it. the easier method is to simply add or subtract the two given equation.

Any way by substitution approach, (by which if you mean substituting the value y, taken from the first equation, in the second equation...) it goes like this...

1st equation: 2x + y = 6 which implies y = 6 - 2x

substituting the value of y in second equation i.e 3x - y = 9

=> 3x - (6 - 2x) = 9

3x - 6 + 2x = 9

5x - 6 = 9

5x = 9 + 6

5x = 15

x = 15/5

x = 3

substituting x in either of the equation will fetch you the value of y which is 0.

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### ilyas_ehUsed to be active here!

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(b)

Here for the convenience sake, take second equation..

i.e. 3x + y = 10

implies y = 10 - 3x

substituting y in equation 1..

2x + 3y = 16

2x + 3 (10 - 3x) = 16

2x + 30 - 9x = 16

-7x = 16 - 30

-7x = -14

i.e x = 2

substitute the value of x in eqn. 2

3x + y = 10

i.e 6 + y = 10

y = 4
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### al-fajr...ism..schismStaff Member

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Assalamu'alaykum,

ilyas_eh, JazakAllah khayr for helping here, I deleted your last post where you worked out the last equation; idris16 should look at the first two examples and have a go at the last one himself.

Then maybe he can see the answer and check it.
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Walaikum assalam warahmatullahi wabarakatuhu

Well,it's easy to do it by addition or subtraction.You may like it.For ex.

b)2x + 3y = 16......(1)
3x + y = 10......(2)

Multiplying equation (1) by 3 and equation (2) by 2 ,we get

6x + 9y = 48......(3)
6x + 2y = 20......(4)

subtracting equation (4) from (3)

6x + 9y = 48......(3)
_ 6x + 2y = 20......(4)
7y = 28

y = 28/7

y = 4

Putting the value of y in equation (2)

3x + 4 = 10
3x = 10 - 4
3x =6
x =6/3

x = 2
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### ilyas_ehUsed to be active here!

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Wa alaykkum assalaam wa rahmatullah

No problem sister. Barak Allahu feeki. Good idea indeed.
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### samiha---------Staff Member

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:salam2:

I actually really like this type of math.

I wish it stayed like this forever and ever, but noo it doesnt do that does it. Has to get all difficult and all that.
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### ilyas_ehUsed to be active here!

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This is the method i personally prefer too. It is quite easier this way when the equation is of second degree or third degree.
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### fceyMember

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Please go to the following website KhanAcademy.org where you will find most subjects explained from very basic to an advanced level.
Most of the videos are about 10 minutes. I feel sure that you will find all your math and science educational needs explained step by step.
I hope this information is of value to you.
Wish you all the best.

Fcey
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### alf2Islam is a way of life

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I would also like to tell Br. Idris if he needs more help with Maths, please look to Youtube! I actually failed math classes as a teenager. But now I am in very advanced maths and PASSING with a high score alhamdulilah with thanks to the wonderful teachers on Youtube!
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### ilyas_ehUsed to be active here!

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Are you still a college/school goer? I left studying proper mathematics after my senior school but now I want to learn out of interest, can you suggest me some good youtube channel?
If you aren't a student, please advise how you've managed to spend time on it. Barak Allahu feek.
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### strive-may-iJunior Member

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Asslaamu Alaikum,
Unless there is a mathematician in you (dont rule out), mostly you will be in area of applied maths or improving your basic mathematics skill. So, you start from where you stopped, and learn maths in areas of your interest. I know a brother, who did it this way. After formal academics, learning is primarily driven by work place demands or self actualization ( out of curiosity, interest, hobbies). Keep learning. You can join a good mathematics forum. May Allah give you more knowledge that benefits others ... Ameen
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As a user suggested earlier, I would suggest http://www.khanacademy.org/ (Youtube channel- http://www.youtube.com/user/khanacademy) for High School mathematics and basic arithmetic (pre-algebra). Ofcourse, It is useful for college-level mathematics too.

But for calculus and differential equation and computational related subjects, I used this - http://nptel.iitm.ac.in/courses.php?disciplineId=111 . But that is just preference, since these professors are from where I come from. So I found it comfortable.

Another resource that I used was - http://tutorial.math.lamar.edu/ ( The so-called "cheat-sheets" here are very useful for quick refresher) and http://eqworld.ipmnet.ru/index.htm

Another very very useful resource is http://mathworld.wolfram.com/ ,

Especially, Step-by-Step Math of Wolfram alpha

http://blog.wolframalpha.com/2009/12/01/step-by-step-math/

Just enter in the equation you want solved , then click the Show steps link to see how you could solve the problem yourself next time without the help of Wolfram Alpha.

I hope it helps, Insha Allah
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### ilyas_ehUsed to be active here!

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wa alaykkum assalaam wa rahmatullahi wa barakaatuh

Many thanks for the advice brother. My work demands proficiency in trigonometry and solving basic algebraic equations. But I find calculus, geometry and Permutations & combinations (and the problem solving that comes with it), interesting. Ameen to your du'a. Jazak Allahu khyir.

Wow bro. Jazak Allahu khyir for this many links. I always used google search but didn't settle with a good math website. Guess TTI can be more useful than one would thought. Barak Allahu feek mate.
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Ameen. wa iyyak.

Wassalamu 'alaikum
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### auss20Junior Member

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Assalamu Alaikum dear brothers and sisters,
actually, i like very much methematics in my shool life. when i saw this page, my mind going to back our school life. anyhow, allah bless to all improve our knoweldge. Jazakumullah
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### fceyMember

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### fceyMember

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Asalamu Alaykum

This website will teach you maths and other subjects from basic to a higher level.

I hope you find it useful.
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substitution method
2x + y = 6 (1
3x − y = 9 (2
since 2x + y = 6
=> y = 6-2x (3
put y=6-2x in =n (2
=> 3x - (6-2x) =9
3x-6+2x=9
=> 5x=9+6
5x=15
x=15/5
=>x=3
now put x=3 in =n (3
=> y=6-2*3=6-6=0
thus x=3 and y = 0
Elimination method
2x + y = 6 (1
3x − y = 9 (2
Add =n (1 and =n (2
=> 5x +0 =15
=> 5x=15
=> x=15/5
=>x=3
now put x= 3 in =n (1
=> 2(3)+y= 6
=>6+y=6
=>y=6-6=0
thus x=3 and y = 0
other methods r cross multiplication etc etc