For f(x, y) = −2x³y² + 2x² + 2y³ + xy, find the partial derivative ∂f/∂y at the point (2, 3).
Multivariable calculus worksheet with answers
1.Easy
f(x, y) = −2x³y² + 2x² + 2y³ + xyP = (2, 3)
fy(2, 3) =
2.Easy
Evaluate I = ∫03 ∫12 (2x·e−y) dy dx over the rectangle 0 ≤ x ≤ 3, 1 ≤ y ≤ 2.
f = 2x·e−y0 ≤ x ≤ 31 ≤ y ≤ 2
I =
3.Medium
For f(x, y) = 5 sin(x + 3y), find the directional derivative Duf at P(2, −1) in the direction towards Q(5, 0).
f(x, y) = 5 sin(x + 3y)P = (2, −1)Q = (5, 0)
Duf =
4.Medium
For f(x, y) = −2x³y − 4x³ + y³ + xy, find the maximum rate of change of f at the point (2, −2), that is |∇f|.
f(x, y) = −2x³y − 4x³ + y³ + xyP = (2, −2)
|∇f| =
5.Hard
The marked points are the critical points of f(x, y) = x³ + y³ − 9xy. Click the saddle point.
f(x, y) = x³ + y³ − 9xy
- 1A (0, 0)
- 2B (3, 3)
6.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 =
Answer key
- 1. fy(2, 3) = −40
- 2. I = 2.093
- 3. Duf = 5.126
- 4. |∇f| = 2.828
- 5. A (0, 0)
- 6. I = 0.1951
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