For f(x, y) = −3x³y − 4x³ + 3xy, find the partial derivative ∂f/∂x at the point (−3, −3).
Multivariable calculus worksheet with answers
1.Easy
f(x, y) = −3x³y − 4x³ + 3xyP = (−3, −3)
fx(−3, −3) =
2.Easy
Evaluate I = ∫25 ∫14 (3y − 1) dy dx over the rectangle 2 ≤ x ≤ 5, 1 ≤ y ≤ 4.
f = 3y − 12 ≤ x ≤ 51 ≤ y ≤ 4
I =
3.Medium
z = 3x³y + x³ − 3y³ with x = −2t + 2 and y = 2t² + 1. Use the chain rule to find dz/dt at t = −1.
z = 3x³y + x³ − 3y³x = −2t + 2y = 2t² + 1t = −1
dz/dt =
4.Medium
For f(x, y) = 3y·e3xy, find the maximum rate of change of f at the point (0.5, 0.5), that is |∇f|.
f(x, y) = 3y·e3xyP = (0.5, 0.5)
|∇f| =
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
The marked points are the critical points of f(x, y) = x³ − 3x + y² + 4y. Click the saddle point.
f(x, y) = x³ − 3x + y² + 4y
- 1A (1, −2)
- 2B (−1, −2)
Answer key
- 1. fx(−3, −3) = 126
- 2. I = 58.5
- 3. dz/dt = −1404
- 4. |∇f| = 12.09
- 5. D = 2048
- 6. B (−1, −2)
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