Evaluate I = ∫12 ∫23 (3x·ey) dy dx over the rectangle 1 ≤ x ≤ 2, 2 ≤ y ≤ 3.
Multivariable calculus worksheet with answers
1.Easy
f = 3x·ey1 ≤ x ≤ 22 ≤ y ≤ 3
I =
2.Easy
Evaluate I = ∫13 ∫24 (−3x²y) dy dx over the rectangle 1 ≤ x ≤ 3, 2 ≤ y ≤ 4.
f = −3x²y1 ≤ x ≤ 32 ≤ y ≤ 4
I =
3.Medium
z = −3x²y² − 4x² − y² − 4xy with x = −t and y = −2t² + 2. Use the chain rule to find dz/dt at t = −1.
z = −3x²y² − 4x² − y² − 4xyx = −ty = −2t² + 2t = −1
dz/dt =
4.Medium
For f(x, y) = −xy³ + 5x³ − 2y³, find the directional derivative Duf at P(1, 2) in the direction towards Q(−1, 3).
f(x, y) = −xy³ + 5x³ − 2y³P = (1, 2)Q = (−1, 3)
Duf =
5.Hard
f(x, y) = x⁴ + y⁴ − 16xy has a critical point at (2, 2). Compute the discriminant D = fxxfyy − fxy² there.
f(x, y) = x⁴ + y⁴ − 16xyP = (2, 2)
D =
6.Hard
f(x, y) = −x³ + 27x − y² + 6y has a critical point at (−3, 3). Compute the discriminant D = fxxfyy − fxy² there.
f(x, y) = −x³ + 27x − y² + 6yP = (−3, 3)
D =
Answer key
- 1. I = 57.13
- 2. I = −156
- 3. dz/dt = −8
- 4. Duf = −22.36
- 5. D = 2048
- 6. D = −36
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