For f(x, y) = −x³y + 2x³ + y³ − 2xy, find the partial derivative ∂f/∂x at the point (2, −2).
Multivariable calculus worksheet with answers
1.Easy
f(x, y) = −x³y + 2x³ + y³ − 2xyP = (2, −2)
fx(2, −2) =
2.Easy
For f(x, y) = 3x³y² − 2x³ − y² + xy, find the partial derivative ∂f/∂y at the point (1, 2).
f(x, y) = 3x³y² − 2x³ − y² + xyP = (1, 2)
fy(1, 2) =
3.Medium
The tangent plane to z = −4xy³ + x³ − y³ − 2xy at the point where (x, y) = (−1, 3) can be written as z = px + qy + c. Find c.
f(x, y) = −4xy³ + x³ − y³ − 2xy(a, b) = (−1, 3)
c =
4.Medium
For f(x, y) = 5xy² + 5x² − 2xy, find the directional derivative Duf at (3, 3) in the direction of v = (−3, −4).
f(x, y) = 5xy² + 5x² − 2xyP = (3, 3)v = (−3, −4)
Duf =
5.Hard
Use polar coordinates to evaluate I = ∬R √(x² + y²) dA, where R is the disc x² + y² ≤ 4.
f = √(x² + y²)0 ≤ r ≤ 20 ≤ θ ≤ 2π
I =
6.Hard
The marked points are the critical points of f(x, y) = x³ − 3x + y² − 4y. Click the local minimum.
f(x, y) = x³ − 3x + y² − 4y
- 1A (1, 2)
- 2B (−1, 2)
Answer key
- 1. fx(2, −2) = 52
- 2. fy(1, 2) = 9
- 3. c = −274
- 4. Duf = −108.6
- 5. I = 16.76
- 6. A (1, 2)
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