Evaluate I = ∫14 ∫01 (4xy² − 2) dy dx over the rectangle 1 ≤ x ≤ 4, 0 ≤ y ≤ 1.
Multivariable calculus worksheet with answers
1.Easy
f = 4xy² − 21 ≤ x ≤ 40 ≤ y ≤ 1
I =
2.Easy
Evaluate I = ∫02 ∫03 (5y − 3) dy dx over the rectangle 0 ≤ x ≤ 2, 0 ≤ y ≤ 3.
f = 5y − 30 ≤ x ≤ 20 ≤ y ≤ 3
I =
3.Medium
The tangent plane to z = −3xy² − 3x³ + 3y² − 2xy at the point where (x, y) = (2, 3) can be written as z = px + qy + c. Find c.
f(x, y) = −3xy² − 3x³ + 3y² − 2xy(a, b) = (2, 3)
c =
4.Medium
For f(x, y) = y·e2xy, find the directional derivative Duf at (2, 0.5) in the direction of v = (−4, 4).
f(x, y) = y·e2xyP = (2, 0.5)v = (−4, 4)
Duf =
5.Hard
Find the critical points of f(x, y) = −x³ + 12x − y² − 4y, classify them, and give the value fmax of f at its local maximum.
f(x, y) = −x³ + 12x − y² − 4y
fmax =
6.Hard
f(x, y) = −x³ + 12x − y² − 6y has a critical point at (2, −3). Compute the discriminant D = fxxfyy − fxy² there.
f(x, y) = −x³ + 12x − y² − 6yP = (2, −3)
D =
Answer key
- 1. I = 4
- 2. I = 27
- 3. c = 141
- 4. Duf = 13.06
- 5. fmax = 20
- 6. D = 24
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