For f(x, y) = ln(x² + 4y²), find the partial derivative ∂f/∂y at the point (1, 0.5).
Multivariable calculus worksheet with answers
1.Easy
f(x, y) = ln(x² + 4y²)P = (1, 0.5)
fy(1, 0.5) =
2.Easy
For f(x, y) = 2y·e3xy, find the partial derivative ∂f/∂x at the point (0.5, 0.5).
f(x, y) = 2y·e3xyP = (0.5, 0.5)
fx(0.5, 0.5) =
3.Medium
For f(x, y) = 3x³e2y, find the direction of steepest ascent at (2, 0.5) as the angle θ from the positive x-axis, in degrees between −180° and 180°.
f(x, y) = 3x³e2yP = (2, 0.5)
θ = °
4.Medium
For f(x, y) = 5 sin(−3x + 2y), find the maximum rate of change of f at the point (0.5, −1), that is |∇f|.
f(x, y) = 5 sin(−3x + 2y)P = (0.5, −1)
|∇f| =
5.Hard
Find the critical points of f(x, y) = −x³ + 27x − y² − 4y, classify them, and give the value fmax of f at its local maximum.
f(x, y) = −x³ + 27x − y² − 4y
fmax =
6.Hard
Use polar coordinates to evaluate I = ∬R √(x² + y²) dA, where R is the upper half of the disc x² + y² ≤ 4 (y ≥ 0).
f = √(x² + y²)0 ≤ r ≤ 20 ≤ θ ≤ π
I =
Answer key
- 1. fy(1, 0.5) = 2
- 2. fx(0.5, 0.5) = 3.176
- 3. θ = 53.13 °
- 4. |∇f| = 16.88
- 5. fmax = 58
- 6. I = 8.378
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