#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 :(

#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)

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

This is why I am a journalism major

#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.

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

thanks guys

#9 Posted by ShaolinSpade (191 posts) -
#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