Answer from answer book:
http://a5.sphotos.ak.fbcdn.net/hphotos-ak-ash4/283310_10150723411825402_893300401_20114706_4158456_n.jpg

My answer:
http://a6.sphotos.ak.fbcdn.net/hphotos-ak-snc6/223087_10150723413820402_893300401_20114740_2684086_n.jpg

Please clarify to me what I'm doing wrong. Their answer is inconsistent with everything I've been doing thus far so it's really confusing.

Question

Answer from answer book:
http://a5.sphotos.ak.fbcdn.net/hphotos-ak-ash4/283310_10150723411825402_893300401_20114706_4158456_n.jpg

My answer:
http://a6.sphotos.ak.fbcdn.net/hphotos-ak-snc6/223087_10150723413820402_893300401_20114740_2684086_n.jpg

Please clarify to me what I'm doing wrong. Their answer is inconsistent with everything I've been doing thus far so it's really confusing.

anonymous · Answer

This is Calc 1, btw.

anonymous · Answer

Does not agree with my eyes >.<

anonymous · Answer

I'm very sorry, I can not help :/

anonymous · Answer

your ananlysis is not corrct i believe  anyhow  the simple sol is  x^3 curve is symetric abt x axis  so  the integral is zero(+ve area cancels with -ve area)

anonymous · Answer

What I don't understand is that early on we are given equal number of exponents in both denominator and numerator (i.e 12n^2/2n^2), but then they choose to divide by the denominator and factor it out and the assume the limit associates with factored out version. Does that make any sense? We don't do this anywhere else and I can't figure out why they're doing it here.