For f(x, y) = x²y + y³ − xy, find the partial derivative ∂f/∂y at the point (2, 3).
Multivariable calculus worksheet with answers
1.Easy
f(x, y) = x²y + y³ − xyP = (2, 3)
fy(2, 3) =
2.Easy
Evaluate I = ∫02 ∫12 (x²y² + 1) dy dx over the rectangle 0 ≤ x ≤ 2, 1 ≤ y ≤ 2.
f = x²y² + 10 ≤ x ≤ 21 ≤ y ≤ 2
I =
3.Medium
For f(x, y) = 4xy² + 3x³ + y³ − xy, find the maximum rate of change of f at the point (−2, −2), that is |∇f|.
f(x, y) = 4xy² + 3x³ + y³ − xyP = (−2, −2)
|∇f| =
4.Medium
For f(x, y) = ln(x² + 2y²), find the maximum rate of change of f at the point (2, −1), that is |∇f|.
f(x, y) = ln(x² + 2y²)P = (2, −1)
|∇f| =
5.Hard
f(x, y) = x² + 4xy + y² − 4x + 4y − 5 has a critical point at (−2, 2). Compute the discriminant D = fxxfyy − fxy² there.
f(x, y) = x² + 4xy + y² − 4x + 4y − 5P = (−2, 2)
D =
6.Hard
Evaluate I = ∬R xy dA, where R is the region between the parabola y = x² and the line y = 4x.
y = x²y = 4xf = xy
I =
Answer key
- 1. fy(2, 3) = 29
- 2. I = 8.222
- 3. |∇f| = 70.94
- 4. |∇f| = 0.9428
- 5. D = −12
- 6. I = 170.7
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