integration help (1 Viewer)

[Continuum]

i'm not namu, but can i answer the Q? lol

well they are basically the same

ull neva be asked to 'use the reveers chain rule

but basically, with the reverse chain rule technically u do use a substitution in ur head, but when u sub in du it turns out 'nicely' ie:

INT (sinxcosx).dx

now u could use a substituion like u=sinx, but by using 'the reverse chain rule' u notice that this will yield an answer that is (1/2)(sinx)^2 + C - ie when u sub in du=cosx.dx it turns out as INT u.du, which is a very simple function, so technically they are the same thing - we call it 'ther reverse chain rule' because when u derive something via teh chain rule, u multiply teh function by it';s derivative at the end, and so if we have an integration with a function multiplied by its derivatrive, its sorta the revers, and that derivcative disappears

if u dont get it, just use a substitution, its the SAME THING, ur just doing more owrking out on the page, which is a good thing!

BUT dont worry about it

if u do 4U u'll get the hang of things and itll be much smoother in the integration chapter

Oooh, thank you thank you.

I get it now.

 

[shaon0]

okay, I apologise if I did

nw

 

[P.T.F.E]

pfft i am a girl. and bdw continuim i was on ur side fool thought u worked it out pretty good and the dude that started this said U were right. that shano dude is up himself tooo far!!

 

[shaon0]

pfft i am a girl. and bdw continuim i was on ur side fool thought u worked it out pretty good and the dude that started this said U were right. that shano dude is up himself tooo far!!

Your the person who came into the thread. Posted up crap and then blamed people when you got the wrong solution yourself.

 

[Z787b]

good on you shan0

 

[proringz]

The x = u^2 - 1 might throw off a few people. Just make it rearrange it to u^2 = x + 1. I always did these kind of integrals with "u^2" and not just "u" as you don't get involved with any nasty ^1/2s and are less prone to making simple errors.

 

[P.T.F.E]

well sorry, no body asked for ur opinion btw i worked out that i haven't covered intergration by substitution yet hence the mistake i made. i've fixed it tho. shano i believe u should get a life the only reason i keep posting comments cause its soooo funni how serious u take this hahaha. jokes on u mate and if u reply to this i will be laughing harder.

 

[tommykins]

well sorry, no body asked for ur opinion btw i worked out that i haven't covered intergration by substitution yet hence the mistake i made. i've fixed it tho. shano i believe u should get a life the only reason i keep posting comments cause its soooo funni how serious u take this hahaha. jokes on u mate and if u reply to this i will be laughing harder.

I think you should shut the fuck up.

 

[shaon0]

well sorry, no body asked for ur opinion btw i worked out that i haven't covered intergration by substitution yet hence the mistake i made. i've fixed it tho. shano i believe u should get a life the only reason i keep posting comments cause its soooo funni how serious u take this hahaha. jokes on u mate and if u reply to this i will be laughing harder.

you should stop lying. It's becoming a really bad habit.
btw, i haven't done integration at school yet. So you should be better off than me.
I'm just lolling at the crap you keep posting lol.

 

[gurmies]

I just want to learn integration =(

 

[Z787b]

I just want to learn integration =(

INTERGRATION IS FUN YOU WILL GET THE HANG OF IT ONCE YOU LEARN IT. MATHS IS A WINDOW OF OPPORTUNITY. THE HSC IS A FIELD TO EXTRAPOLATE YOUR KNOWLEDGE. HAVE FUN

2008 2UNIT, EXT 1 AND 2 MATHS EXAMS WHERE TANGIBLE.
I KNOW BECAUSE I STUDY EFFICENTLY AND EFFECTIVELY

 

[rellenayyy]

this is an ext1 maths forum. not a place to pour your heart out.
regardless. who wants to solve my question ! i feel dumb not getting the answer.

this is definite integrals however. i know you want to.

Int from -3 to 1, dx/sqrt(x+3) using x = u^2 - 3.
i got up to the last part but solutions say 2Int from 0 to 2, du. but i don't get how the u's have cancelled out to make a one.

if you solve this you have def. won this form fight shenangian.
xo.

 

[Z787b]

this is an ext1 maths forum. not a place to pour your heart out.
regardless. who wants to solve my question ! i feel dumb not getting the answer.

this is definite integrals however. i know you want to.

Int from -3 to 1, dx/sqrt(x+3) using x = u^2 - 3.
i got up to the last part but solutions say 2Int from 0 to 2, du. but i don't get how the u's have cancelled out to make a one.

if you solve this you have def. won this form fight shenangian.
xo.

YOU ARE SUCH A 4UNIT LOSER
REAL STUDENTS DONT NEED TO GO POSTING ON THE NET TO FIND HELP
NEXT TIME RETHINK THE LEVEL MATHS YOU ARE DOING. I THINK IT IS CONSUMING YOU.
ANYWAY I DONT CARE ABOUT YOUR PETTY PROBLEM I VE DONE THE HSC THIS YEAR I ACED 4UNIT . ITS AN ARTFORM

 

[gurmies]

brb, hostility

 

[rellenayyy]

YOU ARE SUCH A 4UNIT LOSER
REAL STUDENTS DONT NEED TO GO POSTING ON THE NET TO FIND HELP
NEXT TIME RETHINK THE LEVEL MATHS YOU ARE DOING. I THINK IT IS CONSUMING YOU.
ANYWAY I DONT CARE ABOUT YOUR PETTY PROBLEM I VE DONE THE HSC THIS YEAR I ACED 4UNIT . ITS AN ARTFORM

ya gots to keep it on the chill. jeebus.

 

[Continuum]

this is an ext1 maths forum. not a place to pour your heart out.
regardless. who wants to solve my question ! i feel dumb not getting the answer.

this is definite integrals however. i know you want to.

Int from -3 to 1, dx/sqrt(x+3) using x = u^2 - 3.
i got up to the last part but solutions say 2Int from 0 to 2, du. but i don't get how the u's have cancelled out to make a one.

if you solve this you have def. won this form fight shenangian.
xo.

They're right in changing the boundaries to 0 and 2. When you change dx into du, you have yet to change the boundary values from x to u. Hence, you need to find the value of u which gives you the boundary values for x in the original question.

 

[rellenayyy]

omg. you like shit on my teacher's teaching skills.
what a winner of a person you are !
unlike some others that lurk these virtual halls.

 

[P.T.F.E]

Hahahaha Still Laughing Idiot!!!

 

[Continuum]

Hahahaha Still Laughing Idiot!!!

Shut up bitch.

 

[P.T.F.E]

Hahhahahhahahahhahhahahahahahahahhahah



Sorry That Ur > Gay