Triple Integrals: Find Volume of Region Bounded by x+y, 10, 0, 0

mirandasatterley
Messages
61
Reaction score
0

Homework Statement



Find the volume of the region bounded by z=x+y, z=10, and the planes x=0, y=0

The Attempt at a Solution



If I want to integrate with respect to z,y, then x;
Then I think the limits of integration would be 0≤x≤z-y, so for x the be its largest, set y=0 and z to be large = 10, therefore, 0≤x≤10

for y, keep x constant;
0≤y≤z-x, for y to be large, z should be large, therefore 0≤y≤10-x

and z is already given by the equations in the question; 10≤z≤x+y

I'm not sure that these are right because I have a hard time picturing it in 3D??
Also, Since no function was given, am i just integrating 1, or is a function supposed to be made from the equations in the question?
 
Physics news on Phys.org
mirandasatterley said:
Find the volume of the region bounded by z=x+y, z=10, and the planes x=0, y=0

If I want to integrate with respect to z,y, then x …

Hi mirandasatterley! :smile:

No, integrating three times is not usually a sensible way to do it.

To find a volume, divide into slices, find the area of each slice, and just integrate once.

In this case, use horizontal slices (z = constant), of thickness dz, and integrate the area.
I'm not sure that these are right because I have a hard time picturing it in 3D??

The horizontal slices will be triangles.
Also, Since no function was given, am i just integrating 1, or is a function supposed to be made from the equations in the question?

Yes. :smile:
 
Prove $$\int\limits_0^{\sqrt2/4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx = \frac{\pi^2}{8}.$$ Let $$I = \int\limits_0^{\sqrt 2 / 4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx. \tag{1}$$ The representation integral of ##\arcsin## is $$\arcsin u = \int\limits_{0}^{1} \frac{\mathrm dt}{\sqrt{1-t^2}}, \qquad 0 \leqslant u \leqslant 1.$$ Plugging identity above into ##(1)## with ##u...
Back
Top