For f(x, y) = −3xy + 2x² − 4y³, find the partial derivative ∂f/∂x at the point (−2, 3).
Multivariable calculus worksheet with answers
1.Easy
f(x, y) = −3xy + 2x² − 4y³P = (−2, 3)
fx(−2, 3) =
2.Easy
For f(x, y) = −2xe0.5y, find the mixed second partial derivative ∂²f/∂x∂y at (1, −1).
f(x, y) = −2xe0.5yP = (1, −1)
fxy(1, −1) =
3.Medium
For f(x, y) = −2xy − 4x² + y³, find the directional derivative Duf at (−1, 1) in the direction of v = (−2, 1).
f(x, y) = −2xy − 4x² + y³P = (−1, 1)v = (−2, 1)
Duf =
4.Medium
For f(x, y) = −x³y − x² + 5y², find the maximum rate of change of f at the point (−2, 1), that is |∇f|.
f(x, y) = −x³y − x² + 5y²P = (−2, 1)
|∇f| =
5.Hard
Evaluate I = ∬T (2x + y) dA over the triangle T bounded by y = 0, x = 2 and y = 0.5x.
f = 2x + y0 ≤ x ≤ 20 ≤ y ≤ 0.5x
I =
6.Hard
Evaluate I = ∬T (x + y) dA over the triangle T bounded by y = 0, x = 3 and y = x.
f = x + y0 ≤ x ≤ 30 ≤ y ≤ x
I =
Answer key
- 1. fx(−2, 3) = −17
- 2. fxy(1, −1) = −0.6065
- 3. Duf = −3.13
- 4. |∇f| = 19.7
- 5. I = 3
- 6. I = 13.5
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