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Small query

to integrate xe-x2 limits x=2 and x=0. use the substitution that u=-x2
Reply 1
Avatar for m:)ckel
m:)ckel
14
It is meant to be -4. Who says it isn't?
Reply 2
Avatar for Malik
Malik
12
Misprint surely, no need to worry about you sanity just yet.
Reply 3
Avatar for m:)ckel
m:)ckel
14
Believe in yourself dude!
Reply 4
Avatar for Malik
Malik
12
Just to be on safe side you have integrated this correctly?
INT xe-x² = -e-x²/2 + C
Reply 5
Avatar for Malik
Malik
12
darth_vader05
can you do it like that? i used the substitution that u= -x2


lol no, I just put the final answer in so you can double check that you have intergrated it right.
Reply 6
Avatar for m:)ckel
m:)ckel
14
Well, you notice that the derivative inside the exponential is almost already there on the outside, so you adjust it a bit. You just need to add in that (-1/2) to cancel with the -2x (derivative of -x^2), as in Malik's post.
Reply 7
Avatar for Malik
Malik
12
Yea I know I was to lazy too put in the limits, mockelinho did you just integrate that in your head?
Reply 8
Avatar for m:)ckel
m:)ckel
14
Yeah..I thought that was what you did initially, so I was justifying it. Turns out you didn't do it like that.

But yes, a little 'recognition' of some sort would save time :smile:
Reply 9
Avatar for Malik
Malik
12
mockelinho
Yeah..I thought that was what you did initially, so I was justifying it. Turns out you didn't do it like that.
But yes, a little 'recognition' of some sort would save time :smile:


I should have said nothing and pretended I did :redface: I can see how you have used the recognition but I wouldn't trust myself not to have made careless mistake in my head..guess it gets better with practice.

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