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### In case you'd like to take a look at other tutorials we have, related to Calculus of multiple variables :

 Calculus - Multiple Variables - Part I- Functions of severable variables; limits and continuity Calculus - Multiple Variables - Part 2- Functions of several variables, theorems and co-ordinates Calculus - Multiple Variables - Part 3- Multiple Integrals; double and triple integrals

Functions of several variables ,Theorems and Coordinates

After you learn about this topic, you might benefit from these MCQ Quizzes:

Important points to remember :

Euler’s theorem : If a homogeneous function f(x,y)  of degree n exists then
1. x(∂f/∂x) + y(∂f/∂y) =nf(x,y)
2. x2(∂222y2(∂22= n(n-1)f(x,y)

Taylor’s Theorem : Taylor’s  expansion of one variable can be extended to functions of two variables . If h,k are small
f(x+h,y+k) =f(x,y) +(h ∂/∂x+k ∂/∂y)f+(h ∂/∂x+k ∂/∂y)2f/2! +.......

Jacobians : The Jacobian matrix is the matrix of all first-order partial derivatives of a vector or scalar-valued function with respect to another vector.

Lagrange’s method of  undetermined multipliers : Introducing how we use this to find the maximum or minimum value for a function.

Polar Coordinates :  It is a two-dimensional coordinate system in which each point on a plane is determined by a distance from a fixed point and an angle from a fixed direction.
Cylindrical Coordinates : It is an extension of polar coordinates, but we extend it into the third dimension as well.
Spherical  Coordinates : A spherical coordinate system is a coordinate system for three-dimensional space where the position of a point is specified by three numbers

Here are some of the problems in the tutorial which will help you apply the concepts introduced in the tutorials :

Easy  Problems :

1. Convert the equation r2
2. If  u=(x2221/22u/x22y22z2
3. Convert the equation x22
4. If z=log((x222xy=2yx
5. Convert the equation 2x222
6. Convert the equation ρsin φ = 1  from spherical coordinates to Cartesian coordinates.
1/2

8. Find the Taylor Polynomial of order 3 of f(x) = (x+1)1/2
9.   Find  du/dx  if   u=x222

Moderately difficult Problems :

10. If  f(x,y)=0,  show  that  d22223 where  p= f/ x , q= f/ y ,  r= 2 x2 2 x y , t= 2 / y2
11. Find  the  minimum  value  of  x2223
12.  Find the  extreme  values  of  f(x,y,z)=2x+3y+z   such  that   x22
13.  Expand ex
14.  Find the shortest distance between the line  y=10-2x  and  the ellipse(x2/4)+(y2/9) =1 .
15. Find the minimum distance  from the point  (3,4,15)  to  the  cone   x2+y2=4z2
17.  Find the point on the plane 2x−3y+5z = 19 that is nearest to the  origin.

Difficult  Problems :

18.  Suppose the cost of manufacturing a particular type of box is such  that the base of the box costs three times as much per square foot as the sides and  top. Find the dimensions of the box that minimize the cost for a given volume.
19.  The cone z222
20.  Expand  x2
21.  Expand  ex
22. Expand  exy
23.  Let  f(x,y)  and  g(x,y)  be  two  homogeneous  functions  of  degree  m  and  n  respectively  where  m0.  Let  h=f+g .  If  x h/x  + y h/y =0,  show  that  f=g  for   some   scalar
24.  If  u(x,y)=cos-1x u/x  + y u/y= -1/2 cot u
25.  In   a  plane  triangle,  find  the  maximum  value  of  cosA cosB cosC

## MCQ Quiz #1

Companion MCQ Quiz #1 for this topic- test how much you know about the topic. Your score will be e-mailed to you at the address you provide.

## MCQ Quiz #2 for Multivariate Calculus- Tutorial 2

Read the questions in the document below. Fill up your answers in the answer submission form below it. Your score will be emailed to you.

#### MCQ Quiz: Multivariate Calculus- Tutorial 2

Answer Submission Form for MCQ Quiz #2