For f(x, y) = −2x³y + 4x³ + 4y² + 2xy, find the second partial derivative ∂²f/∂y² at (2, −1).
Multivariable calculus worksheet with answers
1.Easy
f(x, y) = −2x³y + 4x³ + 4y² + 2xyP = (2, −1)
fyy(2, −1) =
2.Easy
For f(x, y) = x²y³ − 5x³ − 3xy, find the partial derivative ∂f/∂y at the point (3, 1).
f(x, y) = x²y³ − 5x³ − 3xyP = (3, 1)
fy(3, 1) =
3.Medium
z = 2x³y² + 2x³ + y² with x = −3t and y = 2t² + 2. Use the chain rule to find dz/dt at t = 1.
z = 2x³y² + 2x³ + y²x = −3ty = 2t² + 2t = 1
dz/dt =
4.Medium
For f(x, y) = ln(x² + y²), find the maximum rate of change of f at the point (−1, 2), that is |∇f|.
f(x, y) = ln(x² + y²)P = (−1, 2)
|∇f| =
5.Hard
The marked points are the critical points of f(x, y) = x³ + y³ − 6xy. Click the local minimum.
f(x, y) = x³ + y³ − 6xy
- 1A (0, 0)
- 2B (2, 2)
6.Hard
The integral I = ∫01.5 ∫x1.5 cos(y²) dy dx cannot be done in this order. Reverse the order of integration and evaluate it.
f = cos(y²)0 ≤ x ≤ y ≤ 1.5
I =
Answer key
- 1. fyy(2, −1) = 8
- 2. fy(3, 1) = 18
- 3. dz/dt = −4450
- 4. |∇f| = 0.8944
- 5. B (2, 2)
- 6. I = 0.389
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