For f(x, y) = 3xy² + 4x² − 3y² + xy, find the partial derivative ∂f/∂y at the point (1, −3).
Multivariable calculus worksheet with answers
1.Easy
f(x, y) = 3xy² + 4x² − 3y² + xyP = (1, −3)
fy(1, −3) =
2.Easy
For f(x, y) = 5x²y + 4x³ − 4y³ − 3xy, find the partial derivative ∂f/∂y at the point (2, 3).
f(x, y) = 5x²y + 4x³ − 4y³ − 3xyP = (2, 3)
fy(2, 3) =
3.Medium
For f(x, y) = −4x²y² + 3x³ − 3y² − xy, find the maximum rate of change of f at the point (1, 2), that is |∇f|.
f(x, y) = −4x²y² + 3x³ − 3y² − xyP = (1, 2)
|∇f| =
4.Medium
The tangent plane to z = 3 sin(3x + y) at the point where (x, y) = (1, 0.5) can be written as z = px + qy + c. Find c.
f(x, y) = 3 sin(3x + y)(a, b) = (1, 0.5)
c =
5.Hard
Find the critical points of f(x, y) = −x³ + 27x − y² − 6y, classify them, and give the value fmax of f at its local maximum.
f(x, y) = −x³ + 27x − y² − 6y
fmax =
6.Hard
Evaluate I = ∬R xy dA, where R is the region between the parabola y = x² and the line y = x.
y = x²y = xf = xy
I =
Answer key
- 1. fy(1, −3) = 1
- 2. fy(2, 3) = −94
- 3. |∇f| = 38.29
- 4. c = 8.78
- 5. fmax = 63
- 6. I = 0.04167
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