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ObsidianVault/College/AU 26/MATH 224 (Multivar)/Chapter 15.1 - Double Integrals over Rectangles.md
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2026-10-07 11:34:24 -07:00

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#uw/notes #uw/class/math224


  • definite integral represents the signed area between a function and the x axis between the two bounds
    • \int_{a}^b f(x) dx
    • for functions with one variable
    • riemann sums: \int_{a}^b f(x) dx = \lim_{ n \to \infty } f(x^*_{k}) \Delta x
  • double integral
    • f(x,y)
    • \int \int_{R} f(x,y) dA
    • represents the signed volume between the xy plane and the graph of z=f(x,y) above the region R
    • defining region
      • R=[a,b] \times [c,d]
      • x values are between a and b , y values are between c and d
    • slice up solid into equations that can be integrated with one variable
    • \int \int_{[a,b] \times [c,d]} f(x,y) dA = \int^b_{a} \int^d_{c}f(x,y)dy dx
    • Fubini's theorem
      • \int_{a}^b \int_{c}^d f(x,y) dy dx = \int_{c}^d \int_{a}^b f(x,y) dx dy
      • can integrate either way (x or y first)