[desijut]

(Original post by raheem94)
isn't easy to integrate.

Wolfram gives a weird answer to it, hence integrating it is probably beyond our knowledge.

I know, but it's worth a try. And that's the fun of it. That it's hard to integrate

[raheem94]

(Original post by desijut)
I know, but it's worth a try. And that's the fun of it. That it's hard to integrate

I won't say it is HARD, it is probably beyond our knowledge.

The answer wolfram gives involves erf(x), i don't know what it is.

[safmaster]

(Original post by raheem94)
...

(Original post by desijut)
...

Just though I'd say, you cannot do analytically. That is what erf(x) shows; it is called the error function, so if you are trying to do the integral indefinitely don't bother . If you however put limits on the integral from infinity to negative infinity, then you can evaluate the integral as you'll notice it is very similar to the normal distribution function (this actually was a STEP question).

And as a side note, the integral is known as the Gaussian integral; more information here: http://en.wikipedia.org/wiki/Gaussian_integral.

[raheem94]

(Original post by safmaster)
Just though I'd say, you cannot do analytically. That is what erf(x) shows; it is called the error function, so if you are trying to do the integral indefinitely don't bother . If you however put limits on the integral from infinity to negative infinity, then you can evaluate the integral as you'll notice it is very similar to the normal distribution function (this actually was a STEP question).

And as a side note, the integral is known as the Gaussian integral; more information here: http://en.wikipedia.org/wiki/Gaussian_integral.

Thanks and +rep for giving the info.

Though it is still a very complicated integral to solve, may be i should concentrate on FP3 rather than this

Did the STEP question gave any hints to solve this?

[safmaster]

(Original post by raheem94)
Thanks and +rep for giving the info.

Though it is still a very complicated integral to solve, may be i should concentrate on FP3 rather than this

Did the STEP question gave any hints to solve this?

Well, it was a STEP II statistics question, which cleverly led you to using the normal distribution tables as it can't be done otherwise. But yeah, I recommend you work on FP3 rather than impossible integrals .

[Rahul.S]

(Original post by raheem94)
Thanks and +rep for giving the info.

Though it is still a very complicated integral to solve, may be i should concentrate on FP3 rather than this

Did the STEP question gave any hints to solve this?

lol people actually tried it! if people want another one try integral of e^x /1+x

you can do what safmaster said which is the best way (i got it from a step question as well) but there is another way via series which can be useful; although using the normal distribution table is better.

anyone that is reading this....this isnt coming up in FP3 so chill brah

[raheem94]

(Original post by Rahul.S)
lol people actually tried it! if people want another one try integral of e^x /1+x

you can do what safmaster said which is the best way (i got it from a step question as well) but there is another way via series which can be useful; although using the normal distribution table is better.

anyone that is reading this....this isnt coming up in FP3 so chill brah

I did understood that is a very complicated integral, so i just input it on wolfram to see how it does it.

I am not going to try your integral because wolfram's answer is a bit weird to me.

[Rahul.S]

(Original post by raheem94)
I did understood that is a very complicated integral, so i just input it on wolfram to see how it does it.

I am not going to try your integral because wolfram's answer is a bit weird to me.

dont just wolfram alpha it that kills it

[fruktas]

(Original post by raheem94)
Thanks and +rep for giving the info.

Though it is still a very complicated integral to solve, may be i should concentrate on FP3 rather than this

Did the STEP question gave any hints to solve this?

Just don't be caught out, if there was an kx infront of it where k is just a constant, you can easily solve it

[raheem94]

(Original post by fruktas)
Just don't be caught out, if there was an kx infront of it where k is just a constant, you can easily solve it

I am not sure what you are saying.

I know how to integrate expressions like .

These can be solved by differentiating , do you mean this?

Though integrating is too much complicated for my maths knowledge .

[fruktas]

(Original post by raheem94)
I am not sure what you are saying.

I know how to integrate expressions like .

These can be solved by differentiating , do you mean this?

Though integrating is too much complicated for my maths knowledge .

Well yes, is exactly the same as , the only thing is, you will have to adjust your constant accordingly to make sure it satisfies the integral.

[Aurum]

Here are three more integrals. All the questions can be done by elementary integration methods, they are hard but doable. For the second question you can use the following result without proof.
where n is a real number.

Q1)
Q2) Given that
Obtain the value of
Q3)
Answers:

Spoiler:

Show

Q1) You can differentiate your answer and check.
Q2)
Q3)

[Rahul.S]

(Original post by Aurum)
Here are three more integrals. All the questions can be done by elementary integration methods, they are hard but doable. For the second question you can use the following result without proof.
where n is a real number.

Q1)
Q2) Given that
Obtain the value of
Q3)

I will give them a go later and get bk

[Omar1994]

can you post the answers please

[Dreamweaver]

How is revision going for everyone? Less than a month to go now. FP2 is fine, could sit the exam tomorrow. FP3 needs more work though. Chapter 2 especially

[number23]

(Original post by Dreamweaver)
How is revision going for everyone? Less than a month to go now. FP2 is fine, could sit the exam tomorrow. FP3 needs more work though. Chapter 2 especially

still got tons of question to get through. im finishing all my physics notes today so i can do fp2 and fp3 solidly throughout june

have you done all the papers? im hoping to do the new spec ones and some of the relevant old ones... if i have time i want to get onto solomon too.

[raheem94]

(Original post by Dreamweaver)
How is revision going for everyone? Less than a month to go now. FP2 is fine, could sit the exam tomorrow. FP3 needs more work though. Chapter 2 especially

Working on FP3 integration, just solved the question you gave in the OP.

Vectors next!

[Rahul.S]

is there a m4 thread around?

i cba to do a new thread.....someone else can get the reps

[snow leopard]

(Original post by Rahul.S)
is there a m4 thread around?

i cba to do a new thread.....someone else can get the reps

There's one already here

[Dreamweaver]

(Original post by number23)
still got tons of question to get through. im finishing all my physics notes today so i can do fp2 and fp3 solidly throughout june

have you done all the papers? im hoping to do the new spec ones and some of the relevant old ones... if i have time i want to get onto solomon too.

Yeah i've done em all. Gonna do some AQA ones before the exam. I'm concentrating on my other subjects atm too

(Original post by raheem94)
Working on FP3 integration, just solved the question you gave in the OP.

Vectors next!

Vectors?

Have fun!