For f(x, y) = 2x²y² − 4x² + y² − 4xy, find the partial derivative ∂f/∂x at the point (−2, −2).
Multivariable calculus worksheet with answers
1.Easy
f(x, y) = 2x²y² − 4x² + y² − 4xyP = (−2, −2)
fx(−2, −2) =
2.Easy
For f(x, y) = −x³y + 5x² + 2xy, find the partial derivative ∂f/∂x at the point (3, −1).
f(x, y) = −x³y + 5x² + 2xyP = (3, −1)
fx(3, −1) =
3.Medium
For f(x, y) = 2 sin(3x − y), find the maximum rate of change of f at the point (0.5, −1), that is |∇f|.
f(x, y) = 2 sin(3x − y)P = (0.5, −1)
|∇f| =
4.Medium
z = 2 ln(x² + y²) with x = −2t + 2 and y = t². Use the chain rule to find dz/dt at t = 0.
z = 2 ln(x² + y²)x = −2t + 2y = t²t = 0
dz/dt =
5.Hard
Find the critical points of f(x, y) = x³ − 3x + y² + 4y, classify them, and give the value fmin of f at its local minimum.
f(x, y) = x³ − 3x + y² + 4y
fmin =
6.Hard
f(x, y) = x³ + y³ + 9xy has a critical point at (−3, −3). Compute the discriminant D = fxxfyy − fxy² there.
f(x, y) = x³ + y³ + 9xyP = (−3, −3)
D =
Answer key
- 1. fx(−2, −2) = −8
- 2. fx(3, −1) = 55
- 3. |∇f| = 5.067
- 4. dz/dt = −4
- 5. fmin = −6
- 6. D = 243
Full step-by-step solutions: practise this topic on examproblems.com.