Evaluate I = ∫12 ∫02 (y) dy dx over the rectangle 1 ≤ x ≤ 2, 0 ≤ y ≤ 2.
Multivariable calculus worksheet with answers
1.Easy
f = y1 ≤ x ≤ 20 ≤ y ≤ 2
I =
2.Easy
For f(x, y) = 3 ln(x² + 2y²), find the partial derivative ∂f/∂y at the point (0.5, 1).
f(x, y) = 3 ln(x² + 2y²)P = (0.5, 1)
fy(0.5, 1) =
3.Medium
z = −3x²y² + 4x² + 5y³ + 4xy with x = 2t + 2 and y = 2t² + 1. Use the chain rule to find dz/dt at t = 1.
z = −3x²y² + 4x² + 5y³ + 4xyx = 2t + 2y = 2t² + 1t = 1
dz/dt =
4.Medium
Use the tangent plane of f(x, y) = 5x³y − 5x³ + 4y³ + 4xy at (3, 1) to approximate f(3.05, 1.2). Give the linear approximation L.
f(x, y) = 5x³y − 5x³ + 4y³ + 4xy(a, b) = (3, 1)(x, y) = (3.05, 1.2)
L =
5.Hard
Find the critical points of f(x, y) = x³ + y³ − 9xy, classify them, and give the value fmin of f at its local minimum.
f(x, y) = x³ + y³ − 9xy
fmin =
6.Hard
The marked points are the critical points of f(x, y) = −x³ + 3x − y² − 6y. Click the local maximum.
f(x, y) = −x³ + 3x − y² − 6y
- 1A (1, −3)
- 2B (−1, −3)
Answer key
- 1. I = 2
- 2. fy(0.5, 1) = 5.333
- 3. dz/dt = −892
- 4. L = 48
- 5. fmin = −27
- 6. A (1, −3)
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