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#1 Posted by TwoOneFive (9791 posts) -

im really stuck on this one. i had to skip the class friday and i have a test tomorrow :(

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please help me asap! thanks in advance. im not a math wiz like i know somebody on here must be. 
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#2 Edited by ThatFrood (3472 posts) -

it's (2/3)(9-(x^2))^(2/3)  
in english: nine minus x squared, to the power of 2/3, multiplied by 2/3
 
 you do a u-substitution. U = 9-x^2 
this makes dU = -2x dx 
 
the substituted equation becomes: integral of u^(1/2) 
which is: 2/3*u^(3/2)

unsubstituting gives you: (2/3)(9-(x^2))^(2/3)      

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#3 Posted by Romination (2846 posts) -
@ThatFrood: d'oh!
Beat me to it.
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#4 Posted by Sjupp (1949 posts) -
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#5 Posted by sarge1445 (747 posts) -

This is why I am a journalism major

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#6 Posted by ThatFrood (3472 posts) -

Also, I just remembered. There's a fancy website out there that only us sexy math people know about. But I'm willing to disclose it to you because I am so sexy and awesome. 
It is called: http://www.wolframalpha.com     
The problem you asked to be answered is something that wolframalpha can do easily. Just type in integrate(squareroot(9-x^2)(-2x)) 
It's like typing into a calculator, except it is even better. Just make sure you get the parentheses right.

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#7 Posted by Sjupp (1949 posts) -
@ThatFrood said:
"

Also, I just remembered. There's a fancy website out there that only us sexy math people know about. But I'm willing to disclose it to you because I am so sexy and awesome. 
It is called: http://www.wolframalpha.com     
The problem you asked to be answered is something that wolframalpha can do easily. Just type in integrate(squareroot(9-x^2)(-2x)) 
It's like typing into a calculator, except it is even better. Just make sure you get the parentheses right.

"
*poke*
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#8 Posted by TwoOneFive (9791 posts) -

thanks guys 

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#9 Posted by ShaolinSpade (191 posts) -
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#10 Posted by TwoOneFive (9791 posts) -
@ThatFrood said:
"

Also, I just remembered. There's a fancy website out there that only us sexy math people know about. But I'm willing to disclose it to you because I am so sexy and awesome. 
It is called: http://www.wolframalpha.com     
The problem you asked to be answered is something that wolframalpha can do easily. Just type in integrate(squareroot(9-x^2)(-2x)) 
It's like typing into a calculator, except it is even better. Just make sure you get the parentheses right.

"
okay,  this site is really awesome.  
it does this problem differently than my professor does it though. i actually figured it out before you guys did this, but i'm still glad i found about these really cool web sites