Evaluate I = ∫12 ∫14 (−x²y + 1) dy dx over the rectangle 1 ≤ x ≤ 2, 1 ≤ y ≤ 4.
Multivariable calculus worksheet with answers
1.Easy
f = −x²y + 11 ≤ x ≤ 21 ≤ y ≤ 4
I =
2.Easy
For f(x, y) = −4x²y² + 2x² + y² + 3xy, find the partial derivative ∂f/∂x at the point (2, −3).
f(x, y) = −4x²y² + 2x² + y² + 3xyP = (2, −3)
fx(2, −3) =
3.Medium
The tangent plane to z = 2y·exy at the point where (x, y) = (0.5, 1) can be written as z = px + qy + c. Find c.
f(x, y) = 2y·exy(a, b) = (0.5, 1)
c =
4.Medium
z = −3x²y + 2x³ − 3y³ with x = t + 1 and y = −2t² + 1. Use the chain rule to find dz/dt at t = 1.
z = −3x²y + 2x³ − 3y³x = t + 1y = −2t² + 1t = 1
dz/dt =
5.Hard
The integral I = ∫01 ∫y1 sin(x²) dx dy cannot be done in this order. Reverse the order of integration and evaluate it.
f = sin(x²)0 ≤ y ≤ x ≤ 1
I =
6.Hard
f(x, y) = x⁴ + y⁴ − 4xy has a critical point at (0, 0). Compute the discriminant D = fxxfyy − fxy² there.
f(x, y) = x⁴ + y⁴ − 4xyP = (0, 0)
D =
Answer key
- 1. I = −14.5
- 2. fx(2, −3) = −145
- 3. c = −3.297
- 4. dz/dt = 120
- 5. I = 0.2298
- 6. D = −16
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