Ask your own question, for FREE!
Mathematics 16 Online
OpenStudy (anonymous):

can someone please help me with double integration

OpenStudy (anonymous):

\[\int\limits_{0}^{1 } \int\limits_{5y}^{5} e^(x^2)\] that should be e^(x^2)

OpenStudy (anonymous):

Ive tried this several times and keep getting the wrong answer

OpenStudy (anonymous):

tell me how you did it please

OpenStudy (anonymous):

we need to change the order of integration i hope you understand it

OpenStudy (anonymous):

i tried to do it dx dy

OpenStudy (anonymous):

but you can solve e^(x^2) dx

OpenStudy (anonymous):

yes i got 2xe^(x^2)

OpenStudy (anonymous):

it is incorrect..

OpenStudy (anonymous):

and then with the limit 10e^10 - 10ye^10y dy

OpenStudy (anonymous):

take the derivative of this and see that it is not e^(x^2)

OpenStudy (anonymous):

[2xe^(x^2)]' = 2(e^(x^2) + x* (2x) * e^(x^2)) and this is not e^(x^2)

OpenStudy (anonymous):

you cant integrate e^(x^2) normally ..

OpenStudy (anonymous):

we have to change limits and hope that then we will be able to integrate..

OpenStudy (anonymous):

ok so how do we do that?

OpenStudy (anonymous):

wait i did a mistake in my sketch

OpenStudy (anonymous):

i deleted and drawing again :

OpenStudy (anonymous):

|dw:1350765581790:dw|

OpenStudy (anonymous):

now if we want to change the order of integration we have to change the limits so if we want dydx we get: \[\int\limits_{0}^{5} \int\limits_{0}^{\frac{ x }{ 5 }} e^{x^2} dydx\]

OpenStudy (anonymous):

tell me if you understand how i changed the limits

OpenStudy (anonymous):

solving this integral gives \[\int\limits_{0}^{5} \frac{ x }{ 5 } \times e^{x^2} - 0 \times e^{x^2} dx = \int\limits_{0}^{5} \frac{ x }{ 5 } \times e^{x^2} dx\]

OpenStudy (anonymous):

now we can do it!! since we may call u = x^2 du = 2xdx so du/2 = xdx \[\int\limits_{0}^{25} \frac{ e^{u} }{ 10 }du\] = (e^25) / 10 - 1/10 = (e^(25) - 1)/10

OpenStudy (anonymous):

Let me know when you read this

OpenStudy (anonymous):

ok i read it

OpenStudy (anonymous):

understand what i did?

OpenStudy (anonymous):

kind of

OpenStudy (anonymous):

im not really sure how the limits changed i guess i thought i got it but i guess i dont

OpenStudy (anonymous):

the first limits was according to dxdy so : |dw:1350766770708:dw|

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!