WORKSHEET ON PARTIAL DERIVATIVES

Problem 1 :

Find the partial derivatives of the following functions at the indicated points.

(1) f (x, y)  =  3x2 − 2xy + y2 + 5x + 2, (2, −5)

(2) g(x, y) = 3x2 + y2 + 5x + 2, (1, −2)

(3) h(x, y, z) = x sin(xy) + z2x, (2, π/4, 1)

(4) G(x, y)  =  e(x+3y) log(x2+y2), (-1, 1)

Solution

Problem 2 :

For each of the following functions find the fx and fy and show that fxy  =  fyx

(1) f (x, y)  =  3x/(y+sinx)

(2) f(x, y)  =  tan-1(x/y)

(3) f(x, y) = cos (x2-3xy)

Solution

Problem 3 :

If

U(x, y, z) = (x2+y2)/xy + 3z2y

find (∂u/∂x), (∂u/∂y) and (∂u/∂z)

Solution

Problem 4 :

If U(x, y, z) = log (x3+y3+z3), find 

(∂u/∂x) + (∂u/∂y) + (∂u/∂z)

Solution

Problem 5 :

For each of the following functions find gxy, gxx, gyy,and gyx.

(i)  g(x, y) = xey+3x2y

(ii)  g(x, y) = log(5x+3y)

(iii) g(x, y) = x2+3xy-7y+cos(5x)

Solution

Problem 6 :

Let

w(x, y, z) = 1/√(x2+y2+z2), (x, y, z) ≠ (0, 0, 0).

Show that (2w/∂x2) + (2w/∂y2(2w/∂z2)

Solution

Problem 7 :

If V(x, y) = ex(x cos y - y sin y), then prove that 

2w/∂x2  = ∂2w/∂y2

Solution

Problem 8 :

If w(x, y) = xy + sin(xy) , then prove that

2w/∂y∂x  = ∂2w/∂x∂y

Solution

Problem 9 :

If V(x, y, z)  =  x3+y3+z3+3xyz, show that 

2v/∂y∂z  = ∂2v/∂z∂y

Solution

Problem 10 :

A firm produces two types of calculators each week, x number of type A and y number of type B . The weekly revenue and cost functions (in rupees) are

R(x, y) = 80x + 90y + 0.04xy − 0.05x2 − 0.05y2 and

C(x, y) = 8x + 6y + 2000 respectively.

(i) Find the profit function P(x, y) ,

(ii) Find P/∂x (1200, 1800) and P/∂y (1200, 1800) and interpret these results.

Solution

Apart from the stuff given above if you need any other stuff in math, please use our google custom search here.

Kindly mail your feedback to v4formath@gmail.com

We always appreciate your feedback.

©All rights reserved. onlinemath4all.com

Recent Articles

  1. SAT Math Resources (Videos, Concepts, Worksheets and More)

    Nov 23, 24 10:01 AM

    SAT Math Resources (Videos, Concepts, Worksheets and More)

    Read More

  2. Digital SAT Math Problems and Solutions (Part - 76)

    Nov 23, 24 09:45 AM

    digitalsatmath63.png
    Digital SAT Math Problems and Solutions (Part - 76)

    Read More

  3. Digital SAT Math Problems and Solutions (Part - 75)

    Nov 21, 24 06:13 AM

    digitalsatmath62.png
    Digital SAT Math Problems and Solutions (Part - 75)

    Read More