What is the solution to a double integral problem with given limits?

Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
5 replies · 1K views
jaydnul
Messages
558
Reaction score
15
Homework Statement
[tex]∫∫x^4ydxdy[/tex]
x [-5,10]
y [-1,1]
(don't know how to do a definite integral in the math code...)

The answer choices are
[itex]A)10^5[/itex]
[itex]B)0[/itex]
[itex]C)-10^{10}[/itex]

The attempt at a solution
[itex]\frac{x^5y}{5}[/itex] evaluated at -5 to 10.

then
[itex]∫20625ydy[/itex] evaluated at -1 to 1.

My final answer is 20625. What did I do wrong?
 
Physics news on Phys.org
Jd0g33 said:
Homework Statement
[tex]∫∫x^4ydxdy[/tex]
x [-5,10]
y [-1,1]
(don't know how to do a definite integral in the math code...)

The answer choices are
[itex]A)10^5[/itex]
[itex]B)0[/itex]
[itex]C)-10^{10}[/itex]

The attempt at a solution
[itex]\frac{x^5y}{5}[/itex] evaluated at -5 to 10.

then
[itex]∫20625ydy[/itex] evaluated at -1 to 1.
Your integral above is OK, but you fouled up when you evaluated the integrand. Try again.
Jd0g33 said:
My final answer is 20625. What did I do wrong?
 
Jd0g33 said:
Homework Statement
[tex]∫∫x^4ydxdy[/tex]
x [-5,10]
y [-1,1]
(don't know how to do a definite integral in the math code...)

The answer choices are
[itex]A)10^5[/itex]
[itex]B)0[/itex]
[itex]C)-10^{10}[/itex]

The attempt at a solution
[itex]\frac{x^5y}{5}[/itex] evaluated at -5 to 10.

then
[itex]∫20625ydy[/itex] evaluated at -1 to 1.

My final answer is 20625. What did I do wrong?

Just fyi, to do a definite integral it's \int_{#}^{#} the _{#} being the bottom number, ^{#} being the top number.
 
So the full integral would look like this:
Code:
$$ \int_{-1}^1 \int_{-5}^{10} x^4 y dx~dy$$

I put this inside HTML code tags so that you could see the script without the browser rendering it. In rendered form, it looks like this:
$$ \int_{-1}^1 \int_{-5}^{10} x^4 y dx~dy$$
 
Oh ok good to know. Thanks guys!