What does a double integral represent?

► My Multiple Integrals course: https://www.kristakingmath.com/multiple-integrals-course

It can be difficult to visualize what a double integral represents, which is why in this video we’ll be answering the question, “What am I finding when I evaluate a double integral?”

In order to answer this question, we’ll compare the double integral to a single integral, so that we understand exactly how to transition from single variable calculus into multivariable calculus. Every piece of the single integral, like the integral, the bounds or limits of integration, the function which is the integrand, and the differential (usually dx) will all translate into a corresponding piece of the double integral.

If we want to describe these with words, we can say that for the single integral, we’re integrating a single variable function f(x) over the interval [a,b], using vertical slices of area, in order to find the total area under the curve f(x) but above the x-axis.

In contrast, we can say that for the double integral, we’re integrating a multivariable function f(x,y) over the region R which is defined for x on the interval [a,b] and for y on the interval [c,d], using vertical slices of volume, in order to find the total volume under the surface f(x,y) but above the xy-plane.

Skip to section:

For the single integral:
0:36 // Sketching a single variable integral
6:32 // Building the area equation for a single integral
7:10 // Moving from the geometric estimation to summation notation
9:24 // Moving from summation notation to the single integral

For the double integral:
10:39 // Sketching a multivariable double integral
20:38 // Building the volume equation for a double integral
21:16 // Moving from the geometric estimation to summation notation
23:22 // Moving from summation notation to the double integral

24:25 // Summary

● ● ● GET EXTRA HELP ● ● ●

If you could use some extra help with your math class, then check out Krista’s website // http://www.kristakingmath.com

● ● ● CONNECT WITH KRISTA ● ● ●

Hi, I’m Krista! I make math courses to keep you from banging your head against the wall. ;)

Math class was always so frustrating for me. I’d go to a class, spend hours on homework, and three days later have an “Ah-ha!” moment about how the problems worked that could have slashed my homework time in half. I’d think, “WHY didn’t my teacher just tell me this in the first place?!”

So I started tutoring to keep other people out of the same aggravating, time-sucking cycle. Since then, I’ve recorded tons of videos and written out cheat-sheet style notes and formula sheets to help every math student—from basic middle school classes to advanced college calculus—figure out what’s going on, understand the important concepts, and pass their classes, once and for all. Interested in getting help? Learn more here: http://www.kristakingmath.com

FACEBOOK // https://www.facebook.com/kristakingmath/
TWITTER // https://twitter.com/KristaKingMath
INSTAGRAM // https://www.instagram.com/kristakingmath/
PINTEREST // https://www.pinterest.com/KristaKingMath/
GOOGLE+ // https://plus.google.com/+Integralcalc/
QUORA // https://www.quora.com/profile/Krista-King

Видео What does a double integral represent? канала Krista King