Ask your own question, for FREE!
Mathematics 13 Online
OpenStudy (anonymous):

calc help!!

OpenStudy (anonymous):

i got 20.25

OpenStudy (danjs):

what are the bounds [a,b] for the integration?

OpenStudy (danjs):

x^3 = 9x

OpenStudy (danjs):

ill put up a graph...

OpenStudy (danjs):

OpenStudy (danjs):

looks like you have 2 regions, [-3,0] of integral of x^3 - integral of 9x, then from [0,3] for integral of 9x- integral of x^3

OpenStudy (danjs):

I think they should be equal from symmetry.

OpenStudy (anonymous):

so it would be 0?

OpenStudy (danjs):

for this i got 81/4 \[\int\limits_{-3}^{0}[x^3]dx - \int\limits_{-3}^{0}(9x)dx = \frac{ 81 }{ 4 }\]

OpenStudy (danjs):

now from 0 to 3...

OpenStudy (anonymous):

oh so i was right? (:

OpenStudy (danjs):

\[\int\limits_{0}^{3}(9x)dx - \int\limits_{0}^{3}x^3dx = \frac{ 81 }{ 4 }\]

OpenStudy (danjs):

notice the top function is 9x in the second region, minus the bottom function x^3

OpenStudy (danjs):

They both come out to the same 81/4, the total area bounded by those two functions is, 2 times 81/4

OpenStudy (danjs):

are you good with evaluating those integrals, i just put the answers up there...

OpenStudy (danjs):

you were right, but you had to double your answer to account for both regions.

OpenStudy (anonymous):

so my final answer would be 40.50? @DanJS

OpenStudy (danjs):

i would just leave it as 81/2

OpenStudy (anonymous):

wait im confused. didnt you just say i have to double it??

OpenStudy (anonymous):

i have to put it into decimal form

OpenStudy (danjs):

yes, each integral came out to 81/4, double that is 81/2

OpenStudy (anonymous):

ohh got it!

OpenStudy (anonymous):

40.50

OpenStudy (danjs):

yeah

Can't find your answer? Make a FREE account and ask your own questions, OR help others and earn volunteer hours!

Join our real-time social learning platform and learn together with your friends!
Can't find your answer? Make a FREE account and ask your own questions, OR help others and earn volunteer hours!

Join our real-time social learning platform and learn together with your friends!