Khan Academy on a Stick
Double and triple integrals
Volume under a surface with double integrals. Triple integrals as well.

Double Integral 1
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Introduction to the double integral

Double Integrals 2
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Figuring out the volume under z=xy^2

Double Integrals 3
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Let's integrate dy first!

Double Integrals 4
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Another way to conceptualize the double integral.

Double Integrals 5
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Finding the volume when we have variable boundaries.

Double Integrals 6
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Let's evaluate the double integrals with y=x^2 as one of the boundaries.
Double integrals
A single definite integral can be used to find the area under a curve. with double integrals, we can start thinking about the volume under a surface!

Triple Integrals 1
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Introduction to the triple integral

Triple Integrals 2
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Using a triple integral to find the mass of a volume of variable density.

Triple Integrals 3
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Figuring out the boundaries of integration.
Triple integrals
This is about as many integrals we can use before our brains explode. Now we can sum variable quantities in threedimensions (what is the mass of a 3D wacky object that has variable mass)!