For f(x, y) = 2x³e−y, find the partial derivative ∂f/∂x at the point (−1, 0.5).
Multivariable calculus worksheet with answers
1.Easy
f(x, y) = 2x³e−yP = (−1, 0.5)
fx(−1, 0.5) =
2.Easy
Evaluate I = ∫03 ∫13 (y + 4) dy dx over the rectangle 0 ≤ x ≤ 3, 1 ≤ y ≤ 3.
f = y + 40 ≤ x ≤ 31 ≤ y ≤ 3
I =
3.Medium
The tangent plane to z = −3xy² + 3x³ − 4y² at the point where (x, y) = (3, 3) can be written as z = px + qy + c. Find c.
f(x, y) = −3xy² + 3x³ − 4y²(a, b) = (3, 3)
c =
4.Medium
z = −x³y² − 4y³ − 3xy with x = 3t − 1 and y = 2t² − 2. Use the chain rule to find dz/dt at t = 1.
z = −x³y² − 4y³ − 3xyx = 3t − 1y = 2t² − 2t = 1
dz/dt =
5.Hard
The integral I = ∫01 ∫y1 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 ≤ 1
I =
6.Hard
Find the critical points of f(x, y) = x³ − 27x + y², classify them, and give the value fmin of f at its local minimum.
f(x, y) = x³ − 27x + y²
fmin =
Answer key
- 1. fx(−1, 0.5) = 3.639
- 2. I = 36
- 3. c = 36
- 4. dz/dt = −24
- 5. I = 0.25
- 6. fmin = −54
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