For f(x, y) = −2x³e0.5y, find the partial derivative ∂f/∂x at the point (2, −1).
Multivariable calculus worksheet with answers
1.Easy
f(x, y) = −2x³e0.5yP = (2, −1)
fx(2, −1) =
2.Easy
For f(x, y) = 3y·e−xy, find the mixed second partial derivative ∂²f/∂x∂y at (−1, 0.5).
f(x, y) = 3y·e−xyP = (−1, 0.5)
fxy(−1, 0.5) =
3.Medium
For f(x, y) = 5xy³ − 3x³ − 4y³ + 3xy, find the maximum rate of change of f at the point (1, 3), that is |∇f|.
f(x, y) = 5xy³ − 3x³ − 4y³ + 3xyP = (1, 3)
|∇f| =
4.Medium
z = −xy − 5y² with x = 3t + 2 and y = −2t². Use the chain rule to find dz/dt at t = 2.
z = −xy − 5y²x = 3t + 2y = −2t²t = 2
dz/dt =
5.Hard
The integral I = ∫00.8 ∫y0.8 ex² dx dy cannot be done in this order. Reverse the order of integration and evaluate it.
f = ex²0 ≤ y ≤ x ≤ 0.8
I =
6.Hard
Use polar coordinates to evaluate I = ∬R √(x² + y²) dA, where R is the quarter of the disc x² + y² ≤ 9 in the first quadrant.
f = √(x² + y²)0 ≤ r ≤ 30 ≤ θ ≤ π/2
I =
Answer key
- 1. fx(2, −1) = −14.56
- 2. fxy(−1, 0.5) = −6.183
- 3. |∇f| = 138.3
- 4. dz/dt = −552
- 5. I = 0.4482
- 6. I = 14.14
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