M25008SelSol2

M25008SelSol2 - Mathematics 250 Fall 2008 Selected...

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Unformatted text preview: Mathematics 250 Fall 2008 Selected Solutions Assignment #2 MM, Exercise 3.2.1: The equation of the tangent plane to the graph of a scalar-valued function f at a given point a is Df ( a )( x- a ) = 0. b) If f ( x y ) = x 2 + y 2 , then Df = [ 2 x 2 y ]. At the point- 1 2 , the equation of the tangent space is [- 2 4 ] ( x y-- 1 2 ) = 0 , or- 2 x + 4 y- 10 = 0, or- x + 2 y- 5 = 0. d) If f ( x y ) = p 4- x 2- y 2 , then Df = h- x 4- x 2- y 2- y 4- x 2- y 2 i . At the point 1 1 , the equation of the tangent plane is- 1 2- 1 2 ( x y- 1 1 ) = 0 , or- 1 2 ( x + y- 2) = 0, or x + y- 2 = 0. e) if f ( x y z ) = xyz , then Df = [ yz xz xy ], At the point 1 2 3 , the equation of the tangent plane is [ 6 3 2 ] (( x y z - 1 2 3 ) = 0 , or 6 x + 3 y + 2 z- 18 = 0. MM, Exercise 3.2.3: Compute the Jacobian or derivative matrices of the following functions. a) f ( x y ) = ( xy x 2 + y 2 ). c) f ( s t ) = ( s cos t s sin t ). e) f ( x y ) = ( x cos y x sin y y . The derivative of Jacobian matrix is the matrix of partial derivatives of the function. By differentiation, we find the following Jacobians: a) y x 2 x 2 y b) cos t- s sin t sin t s cos t c) cos y- x sin y sin y x cos y 1 MM, Exercise 3.2.5: The area of a triangle with sides of lengths a and b , and included angle is A = 1 2 ab sin . The derivative of this is DA = 1 2 [ b sin a sin ab cos ] . 1 For a = 3, b = 4, and = 3 , we have DA = 3 3 3 4 3 . The largest of these components is the third one, so A is most sensitive to a small change in ....
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This note was uploaded on 09/24/2009 for the course MATH 250 taught by Professor Rogerhowe during the Fall '06 term at Yale.

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M25008SelSol2 - Mathematics 250 Fall 2008 Selected...

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