For f(x, y) = 3x²e−y, find the partial derivative ∂f/∂y at the point (2, 0).
Multivariable calculus worksheet with answers
1.Easy
f(x, y) = 3x²e−yP = (2, 0)
fy(2, 0) =
2.Easy
Evaluate I = ∫13 ∫02 (4x²y + 1) dy dx over the rectangle 1 ≤ x ≤ 3, 0 ≤ y ≤ 2.
f = 4x²y + 11 ≤ x ≤ 30 ≤ y ≤ 2
I =
3.Medium
For f(x, y) = 2 ln(x² + 4y²), find the directional derivative Duf at (1, 0.5) in the direction of v = (4, 2).
f(x, y) = 2 ln(x² + 4y²)P = (1, 0.5)v = (4, 2)
Duf =
4.Medium
For f(x, y) = x³y³ + xy, find the maximum rate of change of f at the point (2, −1), that is |∇f|.
f(x, y) = x³y³ + xyP = (2, −1)
|∇f| =
5.Hard
Find the critical points of f(x, y) = −x³ + 27x − y² − 4y, classify them, and give the value fmax of f at its local maximum.
f(x, y) = −x³ + 27x − y² − 4y
fmax =
6.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 =
Answer key
- 1. fy(2, 0) = −12
- 2. I = 73.33
- 3. Duf = 3.578
- 4. |∇f| = 29.07
- 5. fmax = 58
- 6. D = 2048
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