MATA33 Assignment 7 Winter 2022
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Department of Computer & Mathematical Sciences
MATA33
Assignment 7
Winter 2022
Problems:
1. Section 17.2, Pages 742 - 744 # 1, 2, 4 - 10, 14, 18 - 20.
∂z ∂z
∂x ∂y
z implicitly as a function of x and y. If there is a point given, then evaluate the partial derivatives at that point.
(a) 2x2 + 3y2 + 5z2 = 10, (1, 1, 1)
(b) z3 + 2x2 z2 − xy = 1, (1, 2, 1)
(c) ez + ye2 + xyz = 0
3. Find the two points of the form ( − 1, 2, z) that satisfy the equation + y2 = 0 and then evaluate the partial derivatives zz and zy at them. You may assume the equation defines z implicitly as a function of x and y .
4. Section 17.3, Page 745 # 1, 2, 5, 6, 10, 11, 13, 14, 16, 19.
5. Find the equation of the horizontal plane that is tangent to the graph of the function z = G(x, y) = x2 − 4xy − 2y2 + 12x − 12y − 1 .
xy
Y (respectively); and a, b > 0 are constants. Show that the sum of the marginal profits when
x = y is equal to
7. In this problem, it may be useful to refer to the formulas concerning a cylinder in problem #25 on page 612.
(a) Assume we have a cylinder (with a top) of height h and base radius r . If the top, bottom, and wall costs per square metre are a, b, and w dollars respectively, find the cost function
K(h, r, a, b, w) that give the total material cost as a function of h, r, a, b, and w . (b) Find all five partial derivatives of the function K .
(c) Assume now that a = w = 1 and b = 2. Write the function K(h, r, 1, 2, 1).
(d) Consider the level curve L(π) for the function you found in part (c). Find a mathematical relationship for h as a function of r (where h, r > 0 ) that describes the points (h, r) on the level curve L(π). What inequality must r satisfy so that h > 0?
2022-03-29