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# Integration by Recognition watch

1. My teacher skimmed over this quickly at school today, and I was wondering do you need to know this form of integration? Or is there always an alternative? One of my mates from another class claims that it is the only method they use but my teacher said its useless.

Also, could someone explain how this works?

Many Thanks
2. Why the hell is this coursework guy always on. jeeeeez he must get paid.
3. (Original post by oh-my-diddy)
Why the hell is this coursework guy always on. jeeeeez he must get paid.
Do you mean the robot?
4. (Original post by elstevens)
Do you mean the robot?
Lol yes

Trying to finish off my coursework but i'm too tired
5. (Original post by oh-my-diddy)
Lol yes

Trying to finish off my coursework but i'm too tired
Oh dear . It's so late! Or early. Get to bed with you!
6. (Original post by alpha_4)
My teacher skimmed over this quickly at school today, and I was wondering do you need to know this form of integration? Or is there always an alternative? One of my mates from another class claims that it is the only method they use but my teacher said its useless.

Also, could someone explain how this works?

Many Thanks
There's no "technique" to it, you just happen to know the anti-derivative in most cases, or you can figure it out.

e.g. if asked to integrate (x + 2)^-2, you can go a long way around by using a substitution of u = x + 2 and then working it out, or you can recognize that the anti-derivative must be a multiple of (x+2)^-1. So you differentiate (x+2)^-1, which gives you -(x+2)^-2. So you realise that the answer you're looking for is -(x+2)^-1 + c because that differentiates to give you the right thing. All this working out happens in your head, rather than on paper, so it's as if the answer comes out of nowhere, hence recognition.

Once you get good, you can do more complicated things too, but in exams it's better to show the working.
7. (Original post by elstevens)
Oh dear . It's so late! Or early. Get to bed with you!
Yeah i should

Maybe I'll wake up at 9am and continue. Only got a few hundred words left.
8. (Original post by oh-my-diddy)
Yeah i should

Maybe I'll wake up at 9am and continue. Only got a few hundred words left.
Sometimes it can make you feel worse sleeping for only a little bit of time, but I don't want to advise you to stay up! Good luck anyway . I hope you get it all done and it's good .
9. (Original post by elstevens)
Sometimes it can make you feel worse sleeping for only a little bit of time, but I don't want to advise you to stay up! Good luck anyway . I hope you get it all done and it's good .
Lol ah well atleast its something. Probably end up waking up at 11 or 12 or something lol.

Thanks a lot
10. There are 3 types of integration, which one you need will depend on the question, but it's worth learning all three:

-Integration by parts
-Integration by substitution
-Integration by recognition (or spot integration as my teacher called it, as you just have to spot the appropriate integral)

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