Maths, Addmaths and Statistics: Post your doubts here!

[Suchal Riaz]

My friend, this is not Integration by Parts! I know it is easier with substitution but this can also be done directly using the Integration method easily.

nobody is talking about integration by parts! why don't u understand that the way u r doing is the same as substitution but u don't know that the reason u divide by 7 is to make the derivative of inner function a multiple of it so we can treat is like a variable. because it is shorter way of doing this kind of questions without substitution. the method is exactly the same but i know why i divided by 7 but u people say that it is mere rule.
if u want to memorise rules and want to live ur life as shadow of ur real potential then go ahead. but i can not follow rules just because they are true, i want proof and logic.
nobody is convincing u that it is substitution, all that matter is that we now how to do it. but i always want to go one step further. my fault.

 

[Khadija_1234]

can anyone explain all parts of this question?

 

[Saad Mughal]

nobody is talking about integration by parts! why don't u understand that the way u r doing is the same as substitution but u don't know that the reason u divide by 7 is to make the derivative of inner function a multiple of it so we can treat is like a variable. because it is shorter way of doing this kind of questions without substitution. the method is exactly the same but i know why i divided by 7 but u people say that it is mere rule.
if u want to memorise rules and want to live ur life as shadow of ur real potential then go ahead. but i can not follow rules just because they are true, i want proof and logic.
nobody is convincing u that it is substitution, all that matter is that we now how to do it. but i always want to go one step further. my fault.

Ok, so when differentiating 7x, what do you do, please elaborate.

 

[Suchal Riaz]

Ok, so when differentiating 7x, what do you do, please elaborate.

if we add 7 inside integral and divide by 7 outside integral we get derivative of 7 outside. by reverse if u do whole substitution in head, 7*dx=du where u=(7x+8) so integral becomes 1/7 integral(u^1/3)du add power and divide u get 1/7*4/3(7x+4)^3/4 same result got in head with some reason why we are doing this way.
i got my mistake, when function of degree 1 is inside integral we can do reverse chain rule and it works fine as it's derivative is always a constant.
but examiner report still referred to correct name of this process.
i m not doing trig substitution as i dont expect it to come. substitution helped me clear my concepts of some things which i memorised earlier.
thanks for explaining me.

 

[Saad Mughal]

if we add 7 inside integral and divide by 7 outside integral we get derivative of 7 outside. by reverse if u do whole substitution in head, 7*dx=du where u=(7x+8) so integral becomes 1/7 integral(u^1/3)du add power and divide u get 1/7*4/3(7x+4)^3/4 same result got in head with some reason why we are doing this way.
i got my mistake, when function of degree 1 is inside integral we can do reverse chain rule and it works fine as it's derivative is always a constant.
but examiner report still referred to correct name of this process.
i m not doing trig substitution as i dont expect it to come. substitution helped me clear my concepts of some things which i memorised earlier.
thanks for explaining me.

No problem
You find substitution easy, I find this easy, it is a matter of a persons choice as to what method he adopts. Anyways, trig. subs. won't come. I'm sure of it.

 

[Suchal Riaz]

can anyone explain all parts of this question?

1- fails: 0.1 passes: 0.9
fail then pass, so 0.1*0.9=0.09
2-passes in first: 0.9
passes in second attempt: 0.09
0.9+0.09=0.99
3-0.1*0.1*0.1=0.001
4- i think shorter way will be 1-0.001=0.999 try taking all posinilities maybe i m wrong
b)
1- 0.1n
2- =1-(0.1)^n

 

[Haris Bin Zahid]

the rule which allows you to take a function as a single variable is derived from u-substitution. and by substitution it is simpler and can be done in mind. examiner report states that "Those candidates who realised the need for substitution found this an easy mark."

Seriously, you should aim those guns in your avatar towards yourself.
The extract you've quoted is actually a comment of examiner about another part of the question, not the one you're referring to. Read the examiner report which corresponds to a particular question.

 

[Saad Mughal]

1- fails: 0.1 passes: 0.9
fail then pass, so 0.1*0.9=0.09
2-passes in first: 0.9
passes in second attempt: 0.09
0.9+0.09=0.99
3-0.1*0.1*0.1=0.001
4- i think shorter way will be 1-0.001=0.999 try taking all posinilities maybe i m wrong
b)
1- 0.1n
2- =1-(0.1)^n

All these are correct except for two tiny mistakes.
In 4- it will be 1-0.0001 = 0.999 since we're taking out the probability of fail in first four months.
In b, 1- it will be (0.1)^n.

 

[Suchal Riaz]

Seriously, you should aim those guns in your avatar towards yourself.
The extract you've quoted is actually a comment of examiner about another part of the question, not the one you're referring to. Read the examiner report which corresponds to a particular question.

i read examiner report of part (a) of same question so i thought that it is about part (b)
i have confessed my mistake still if u want to give me saza-e-moot then i am ready

 

[josephsai]

there is no paper three for add maths

sorry i thought meant A level maths, i finished IGCSE last yr and in add math integration stops at substitution.

 

[usama321]

http://papers.xtremepapers.com/CIE/...(Calculator Version) (4024)/4024_w07_qp_2.pdf

can someone please explain question 9 c part 4, angle DCF? thanks

 

[usama321]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Mathematics D (Calculator Version) (4024)/4024_w07_qp_2.pdf

can someone please explain question 9 c part 4, angle DCF? thanks

ohk, i got it already

 

[Ishrar Afrida]

An ocean liner is travelling at 36 km h
01 on a bearing of 090°. At 0600 hours the liner, which is
90 km from a lifeboat and on a bearing of 315° from the lifeboat, sends a message for assistance.
The lifeboat sets off immediately and travels in a straight line at constant speed, intercepting the
liner at 0730 hours. Find the speed at which the lifeboat travels.

May/June-2003 P-1 Q-4. ER says the answer is 42.9 km/h but I got 28.9 km/h. Can anybody check which one is actual?

 

[Suchal Riaz]

An ocean liner is travelling at 36 km h
01 on a bearing of 090°. At 0600 hours the liner, which is
90 km from a lifeboat and on a bearing of 315° from the lifeboat, sends a message for assistance.
The lifeboat sets off immediately and travels in a straight line at constant speed, intercepting the
liner at 0730 hours. Find the speed at which the lifeboat travels.

May/June-2003 P-1 Q-4. ER says the answer is 42.9 km/h but I got 28.9 km/h. Can anybody check which one is actual?

i did it geometrically, but with vecor way answer is same:

 

[Ishrar Afrida]

i did it geometrically, but with vecor way answer is same:View attachment 23611

WOW you're a genius. But I did not get how is the included angle is 45 degrees? :/

 

[Suchal Riaz]

WOW you're a genius. But I did not get how is the included angle is 45 degrees? :/

the bearing is 315, so anticlockwise angle between north and boat is 45, if we extend north and liner's direction it is 90deg liner is going 090 deg(east). one angle is 90 and other is 45 so the third has to be 45 as well.

 

[nidz]

Does anyone have the examiner report for Addmaths nov 11 paper?
It's not uploaded here :/

 

[Saad Mughal]

Does anyone have the examiner report for Addmaths nov 11 paper?
It's not uploaded here :/

Here you go.

 

[Suchal Riaz]

Does anyone have the examiner report for Addmaths nov 11 paper?
It's not uploaded here :/

winter 2011 in this thread go to the link of o levels then find the examiner reports there

 

[sweetiepie]

Solve
x-2[3x-2(x+1)_5] = 16