Evaluate I = ∫23 ∫02 (3x²y + 5) dy dx over the rectangle 2 ≤ x ≤ 3, 0 ≤ y ≤ 2.
Multivariable calculus worksheet with answers
1.Easy
f = 3x²y + 52 ≤ x ≤ 30 ≤ y ≤ 2
I =
2.Easy
For f(x, y) = −x³y³ + 4y² + xy, find the second partial derivative ∂²f/∂x² at (−1, −1).
f(x, y) = −x³y³ + 4y² + xyP = (−1, −1)
fxx(−1, −1) =
3.Medium
For f(x, y) = −xy + 5x² + 3y³, find the directional derivative Duf at (−2, −1) in the direction of v = (3, 0).
f(x, y) = −xy + 5x² + 3y³P = (−2, −1)v = (3, 0)
Duf =
4.Medium
For f(x, y) = sin(2x + 3y), find the maximum rate of change of f at the point (2, −1), that is |∇f|.
f(x, y) = sin(2x + 3y)P = (2, −1)
|∇f| =
5.Hard
Find the critical points of f(x, y) = 3x² − xy + 2y² + 9x + 10y + 5, classify them, and give the value fmin of f at its local minimum.
f(x, y) = 3x² − xy + 2y² + 9x + 10y + 5
fmin =
6.Hard
Use polar coordinates to evaluate I = ∬R y dA, where R is the upper half of the disc x² + y² ≤ 9 (y ≥ 0).
f = y0 ≤ r ≤ 30 ≤ θ ≤ π
I =
Answer key
- 1. I = 48
- 2. fxx(−1, −1) = −6
- 3. Duf = −19
- 4. |∇f| = 1.948
- 5. fmin = −19
- 6. I = 18
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