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Q 39.

Expert-verified
Calculus
Found in: Page 944
Calculus

Calculus

Book edition 1st
Author(s) Peter Kohn, Laura Taalman
Pages 1155 pages
ISBN 9781429241861

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Short Answer

In Exercises 37-42, use the partial derivatives of role="math" localid="1650186824938" fx,y=xy and the point e,3 specified to

a find the equation of the line tangent to the surface defined by the function in the x direction,

b find the equation of the line tangent to the surface defined by the function in the y direction, and

c find the equation of the plane containing the lines you found in parts a and b.

Part a, The equation of the line tangent to the surface defined by the function in the x direction is

x=e+t, y=3, z=e3+3e2t

Part b, The equation of the line tangent to the surface defined by the function in the y direction is

x=e, y=3+t, z=e3+e3t

Part c, The equation of the plane containing the lines you found in parts a and b is

localid="1650216415404" 3e2x+e3y-z=5e3

See the step by step solution

Step by Step Solution

Part (a) Step 1. Explanation of part a, Finding equation of tangent in x direction

The line tangent to the surface at a,b,fa,b in the x direction is given by the parametric equation

x=a+t, y=b, z=fa,b+fxa,bt

Now we have function fx,y=xy and point role="math" localid="1650215016730" e,3

So a=e, b=3, fa,b=e3, fxa,b=3e2

Therefore, equation of tangent in x direction is

x=e+t, y=3, z=e3+3e2t

Part (b)  Step 1. Explanation of part b, Finding equation of tangent in y direction

The line tangent to the surface at a,b,fa,b in the y direction is given by the parametric equation

x=a, y=b+t, z=fa,b+fya,bt

Now we have function fx,y=xy and point e,3

So role="math" localid="1650215656272" a=e, b=3, fa,b=e3, fya,b=e3

Therefore, equation of tangent in y direction is

x=e, y=3+t, z=e3+e3t

Part (c)  Step 1. Explanation of part c, Finding equation of plane

The equation of plane containing the given lines and point is

fxa,bx-a+fya,by-b=z-fa,b

3e2x-e+e3y-3=z-e3

3e2x-3e3+e3y-3e3=z-e3

3e2x+e3y-z=5e3

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