For f(x, y) = −2xy² + x³ + 4xy, find the partial derivative ∂f/∂x at the point (3, −3).
Multivariable calculus worksheet with answers
1.Easy
f(x, y) = −2xy² + x³ + 4xyP = (3, −3)
fx(3, −3) =
2.Easy
Evaluate I = ∫23 ∫14 (3y − 4) dy dx over the rectangle 2 ≤ x ≤ 3, 1 ≤ y ≤ 4.
f = 3y − 42 ≤ x ≤ 31 ≤ y ≤ 4
I =
3.Medium
For f(x, y) = −2x³y³ + x² − 5y³ + 2xy, find the directional derivative Duf at (2, −1) in the direction of v = (−2, −3).
f(x, y) = −2x³y³ + x² − 5y³ + 2xyP = (2, −1)v = (−2, −3)
Duf =
4.Medium
The tangent plane to z = −xy² − 2x² + 2y² + 2xy at the point where (x, y) = (2, −1) can be written as z = px + qy + c. Find c.
f(x, y) = −xy² − 2x² + 2y² + 2xy(a, b) = (2, −1)
c =
5.Hard
Use polar coordinates to evaluate I = ∬R (x² + y²) dA, where R is the quarter of the disc x² + y² ≤ 2.25 in the first quadrant.
f = x² + y²0 ≤ r ≤ 1.50 ≤ θ ≤ π/2
I =
6.Hard
f(x, y) = x⁴ + y⁴ − 16xy has a critical point at (−2, −2). Compute the discriminant D = fxxfyy − fxy² there.
f(x, y) = x⁴ + y⁴ − 16xyP = (−2, −2)
D =
Answer key
- 1. fx(3, −3) = −3
- 2. I = 10.5
- 3. Duf = 34.67
- 4. c = 14
- 5. I = 1.988
- 6. D = 2048
Full step-by-step solutions: practise this topic on examproblems.com.