Evaluate I = ∫14 ∫13 (−3y + 1) dy dx over the rectangle 1 ≤ x ≤ 4, 1 ≤ y ≤ 3.
Multivariable calculus worksheet with answers
1.Easy
f = −3y + 11 ≤ x ≤ 41 ≤ y ≤ 3
I =
2.Easy
For f(x, y) = 5 sin(3x + 3y), find the partial derivative ∂f/∂y at the point (0.5, 0.5).
f(x, y) = 5 sin(3x + 3y)P = (0.5, 0.5)
fy(0.5, 0.5) =
3.Medium
For f(x, y) = 3y·exy, find the directional derivative Duf at (−1, 2) in the direction of v = (−3, 3).
f(x, y) = 3y·exyP = (−1, 2)v = (−3, 3)
Duf =
4.Medium
For f(x, y) = x³y + x² − y³ + xy, find the directional derivative Duf at P(−2, −1) in the direction towards Q(−4, −3).
f(x, y) = x³y + x² − y³ + xyP = (−2, −1)Q = (−4, −3)
Duf =
5.Hard
The integral I = ∫00.8 ∫y0.8 1/(1 + x²)² dx dy cannot be done in this order. Reverse the order of integration and evaluate it.
f = 1/(1 + x²)²0 ≤ y ≤ x ≤ 0.8
I =
6.Hard
The marked points are the critical points of f(x, y) = x⁴ + y⁴ − 16xy. Click the saddle point.
f(x, y) = x⁴ + y⁴ − 16xy
- 1A (2, 2)
- 2B (0, 0)
- 3C (−2, −2)
Answer key
- 1. I = −30
- 2. fy(0.5, 0.5) = −14.85
- 3. Duf = −1.435
- 4. Duf = 21.21
- 5. I = 0.1951
- 6. B (0, 0)
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