For f(x, y) = 2x³y + 2x³ + 5y² − xy, find the partial derivative ∂f/∂y at the point (−3, 2).
Multivariable calculus worksheet with answers
1.Easy
f(x, y) = 2x³y + 2x³ + 5y² − xyP = (−3, 2)
fy(−3, 2) =
2.Easy
For f(x, y) = 5 sin(−3x − 2y), find the partial derivative ∂f/∂x at the point (1, −1).
f(x, y) = 5 sin(−3x − 2y)P = (1, −1)
fx(1, −1) =
3.Medium
The tangent plane to z = −3x²y² + 3x³ + 4y² + 3xy at the point where (x, y) = (3, −2) can be written as z = px + qy + c. Find c.
f(x, y) = −3x²y² + 3x³ + 4y² + 3xy(a, b) = (3, −2)
c =
4.Medium
For f(x, y) = ln(x² + 3y²), find the directional derivative Duf at (0.5, 1) in the direction of v = (−1, 4).
f(x, y) = ln(x² + 3y²)P = (0.5, 1)v = (−1, 4)
Duf =
5.Hard
The integral I = ∫01.2 ∫y1.2 cos(x²) dx dy cannot be done in this order. Reverse the order of integration and evaluate it.
f = cos(x²)0 ≤ y ≤ x ≤ 1.2
I =
6.Hard
Use polar coordinates to evaluate I = ∬R e−(x² + y²) dA, where R is the disc x² + y² ≤ 2.25.
f = e−(x² + y²)0 ≤ r ≤ 1.50 ≤ θ ≤ 2π
I =
Answer key
- 1. fy(−3, 2) = −31
- 2. fx(1, −1) = −8.105
- 3. c = 164
- 4. Duf = 1.716
- 5. I = 0.4957
- 6. I = 2.81
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