Mathematics: Post your doubts here!

[Abid357]

Re: Maths made easy =) stuck sumwhere?Ask ur doubts here!!

Thanks for the info . Hmm.. my working :?. Ok hang on..

 

[Abid357]

Re: Maths made easy =) stuck sumwhere?Ask ur doubts here!!

One question... in the elimination method, does it really matter whether I solve x or y the first? Will that have any effect on the final answer?

 

[CaptainDanger]

Re: Maths made easy =) stuck sumwhere?Ask ur doubts here!!

One question... in the elimination method, does it really matter whether I solve x or y the first? Will that have any effect on the final answer?

NO! DO as you like... You can do it either way...

 

[CaptainDanger]

Re: Maths made easy =) stuck sumwhere?Ask ur doubts here!!

Yeah Salman typed down the wrong equations...

2x+3y=11 ------>1
3x-5y=-12 ------>2

Eliminating Method

Its upto you that you want to eliminate the x or y....
I want to eliminate x
so the coefficients of x are 2 and 3...

Take there LCM which is 6...

Now you need to make these both 2 and 3 six... For that you have to multiply the 1st equation with 3
After you do it becomes
6x+9y=33
And the second equation with 2
After you it becomes
6x-10y=-24

6x+9y=33
6x-10y=-24

^^^^WRITE THEM AS I DID^^^^^
Subtract them now.... So first you need to change the signs of 6x-10y=-24 which becomes -6x+10y=24... (SUBTRACTING SO YOU NEED TO FIRST CHANGE THE SIGNS, IN ADDITION YOU DON'T HAVE TO BECAUSE SOMETIMES USING ADDITION THEY ARE CANCELED OUT HERE IF YOU ADD THEY BECOME 12x SO WE NEED TO SUBTRACT )

6x+9y=33
-6x+10y=24

Now 6x-6x canceled...
9y+10y=19y and 33 + 24 = 57
It becomes like this
19y=57
y=57/19=3

Now put this y value in any of the above equation you want to to find the value of x... Putting it in the 1st one....
2x+3y=11
2x+3(3)=11
2x+9=11
2x=2
x=2/2=1

so x=1 and y=3!

!....I AM NOT GOOD AT EXPLAINING THINGS SO I HOPE YOU GET IT....!

 

[Abid357]

Re: Maths made easy =) stuck sumwhere?Ask ur doubts here!!

Wow, jazak Allahu khairan! I tried to solve using the substitution method right now, here's the attached file. What could have possibly gone wrong? And thanks very much again for the answer

 

[XPFMember]

Re: Maths made easy =) stuck sumwhere?Ask ur doubts here!!

Assalamoalaikum!!
ok so i've spotted ur first mistake!! well when u multiply 3 and 1/2 u get 3/2 ...right??

similarly 3[(11 – 3y) / 2] = (33-9y) /2

denominator is 2 not 6!!

let me see if there's any other mistake!!

 

[SalmanPakRocks]

Re: Maths made easy =) stuck sumwhere?Ask ur doubts here!!

I GAVE AN EXAMPLE CAPTAIN !!

 

[XPFMember]

Re: Maths made easy =) stuck sumwhere?Ask ur doubts here!!

well that was the only mistake...try doing it now and u'll get y=3

 

[Abid357]

Re: Maths made easy =) stuck sumwhere?Ask ur doubts here!!

Assalamoalaikum!!
ok so i've spotted ur first mistake!! well when u multiply 3 and 1/2 u get 3/2 ...right??

similarly 3[(11 – 3y) / 2] = (33-9y) /2

denominator is 2 not 6!!

let me see if there's any other mistake!!

Fantastic ! Hmm so that was it... the denominator never changes... cool, thanks so much really, and sorry for bothering hehe. Alhamdulillah, can sleep at ease now

 

[XPFMember]

Re: Maths made easy =) stuck sumwhere?Ask ur doubts here!!

yes it will only change in the case when there is a denominator in the no. u r multipllying...for eg. if it was 3/7 instead of 3...then 7 and 2 wud get multiplied

 

[XPFMember]

Re: Maths made easy =) stuck sumwhere?Ask ur doubts here!!

Kindly refrain from posting 'useless, needless, futile' (I dont know which word best describes those) posts here.

 

[WayneRooney10]

Re: Maths made easy =) stuck sumwhere?Ask ur doubts here!!

Can anyone briefly explain functions?

 

[SalmanPakRocks]

Re: Maths made easy =) stuck sumwhere?Ask ur doubts here!!

Here are the notes

 

[XPFMember]

Re: Maths made easy =) stuck sumwhere?Ask ur doubts here!!

check the attachment

it's gud for revision

 

[WayneRooney10]

Re: Maths made easy =) stuck sumwhere?Ask ur doubts here!!

This is for O level. My level isnt that high...i think

 

[XPFMember]

Re: Maths made easy =) stuck sumwhere?Ask ur doubts here!!

o level and IGCSE is the same level

 

[WayneRooney10]

Re: Maths made easy =) stuck sumwhere?Ask ur doubts here!!

Oh! okay...but i only need help in solving functions...like...f(x)= 2x-5.....i always get confused.

 

[XPFMember]

Re: Maths made easy =) stuck sumwhere?Ask ur doubts here!!

anyways
in functions u shud know how to find solutions
eg. f(x) = 2x + 7
g(x) = 3x^2
u shud be able to do the following

(i) f(5)
(ii) f(x) =15
(iii) f^-1 (15)
(iv) f^-1(x)
(v) fg(x)


this is what i remember now...if u have doubts let me know

 

[SalmanPakRocks]

Re: Maths made easy =) stuck sumwhere?Ask ur doubts here!!

Oh! okay...but i only need help in solving functions...like...f(x)= 2x-5.....i always get confused.

post the question here and we will guide you !!

 

[Pernee26]

Re: Maths made easy =) stuck sumwhere?Ask ur doubts here!!

Please can you solve October/November 2008 paper 4 Q3 Q8 and Q10 ?
Oh and can you give me useful tips on Loci and how Cambridge usually gives questions on this topic ?
Your help will be highly appreciated !

Q 8

(a)
x= 78° Answer (alternate angles)

y=180°-36°=144°Answer (Here you have to use the property that sum of opposite sides of CYCLIC quadrilateral = 180°)

z= 180°-78°=102° Answer again same property as above...

(b) The some of x+y needs to be 180° if they are parallel but its not the case so they are not... Taking alternate angles again... But that is only possible if they are parallel...

(c) Angle subtended at center is always double of the angle at the circumference from the same CHORD... So for E0C draw line EC now apply the property...
E0C=144/2=72° Answer

(d) Two sides equal so two angles equal... Its a triangle you can see... So 180°-78°=102° As both the angles are same so divide 102° by 2 = 51° Answer....

Thank you Can you do Q 3 and Q 10 from the same past paper as well please.
Here is the link http://www.xtremepapers.me/CIE/Cambridge IGCSE/0580 - Mathematics/0580_w08_qp_04.pdf