For f(x, y) = sin(2x + y), find the partial derivative ∂f/∂y at the point (0.5, −1).
Multivariable calculus worksheet with answers
1.Easy
f(x, y) = sin(2x + y)P = (0.5, −1)
fy(0.5, −1) =
2.Easy
For f(x, y) = 3 ln(x² + 4y²), find the partial derivative ∂f/∂y at the point (−1, 1).
f(x, y) = 3 ln(x² + 4y²)P = (−1, 1)
fy(−1, 1) =
3.Medium
For f(x, y) = −x³y² + 3x³ + 5y² + 2xy, find the direction of steepest ascent at (1, −2) as the angle θ from the positive x-axis, in degrees between −180° and 180°.
f(x, y) = −x³y² + 3x³ + 5y² + 2xyP = (1, −2)
θ = °
4.Medium
The tangent plane to z = x²y² − 4x³ + y³ + 3xy at the point where (x, y) = (3, −1) can be written as z = px + qy + c. Find c.
f(x, y) = x²y² − 4x³ + y³ + 3xy(a, b) = (3, −1)
c =
5.Hard
Use polar coordinates to evaluate I = ∬R (x² + y²) dA, where R is the upper half of the disc x² + y² ≤ 9 (y ≥ 0).
f = x² + y²0 ≤ r ≤ 30 ≤ θ ≤ π
I =
6.Hard
Find the area I = ∬R 1 dA of the region R between the parabola y = x² and the line y = x.
y = x²y = xf = 1
I =
Answer key
- 1. fy(0.5, −1) = 1
- 2. fy(−1, 1) = 4.8
- 3. θ = −116.6 °
- 4. c = 200
- 5. I = 63.62
- 6. I = 0.1667
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