surface area

course Mth 173

2/18 10

Question: `q query problem 1.6.7 5th ed; 1.6.12 4th; 1.6.9 (was 1.10.16)cubic polynomial representing graph. What cubic polynomial did you use to represent the graph?

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Your solution:

X = -2 , 1, 5

y-int of 2

2 = 10k

K = .2

K(.2) = [X = .2(x+2)(x-1)(x-5)]

confidence rating #$&*: 3

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Given Solution:

*&*& The given function has zeros at x = -2, 1, 5, so y = k (x+2)(x-1)(x-5).

At x = 0 the function has value 2, so 2 = k (0+2)(0-1)(0-5), or 2 = 10 k.

Thus k = .2 and the function is

y = .2 ( x+2)(x-1)(x-5). **

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Self-critique (if necessary): OK

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Self-critique rating #$&*: 3

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Question: `q Query problem 1.6.14 5th ed; 1.6.15 4th ed; 1.6.15 (formerly 1.4.19) s = .01 w^.25 h^.75what is the surface area of a 65 kg person 160 cm tall?

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Your solution:

S = .01(65^.25) (160^.75) =

S = 1.277 m

confidence rating #$&*: 3

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Given Solution:

** Substituting we get

s = .01 *65^.25 *160^.75 = 1.277meters^2 **

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Self-critique (if necessary): I must square the surface area of a 2 dimensional shape.

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Self-critique rating #$&*: 1

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Question: `q What is the weight of a person 180 cm tall whose surface area is 1.5 m^2?

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Your solution:

1.5 = .01 (w^.25)(180^.75) =

150 = (w^.25)(180^.75)

3.052 = w^.25

W = 86.806 kg

confidence rating #$&*: 3

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Given Solution:

** Substituting the values we get

1.5 = .01 w^.25*180^.75 . Dividing both sides by 180:

1.5/180^.75

.01w^.25. Dividing both sides by .01:

3.05237 = w^.25 Taking the fourth power of both sides:

w = 3.052^4 = 86.806 **

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Self-critique (if necessary): OK

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Self-critique rating #$&*: 3

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Question: `q For 70 kg persons what is h as a function of s?

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Your solution:

S = .01(70^.25)(h^.75)

S = .029(h^.75)

S = 2.333h

s is a multiply of h^.75, so s can't be a multiple of h

H = 2.333 / s

confidence rating #$&*: 2

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Given Solution:

** Substituting 70 for the weight we get

s = .01 *70^.25 h^.75

s = .02893 h^.75

s/.02893 = h^.75

34.60 s = h^.75

Taking the 1/.75 = 4/3 power of both sides:

(34.60 s)^(4/3) = h

h = 111 s^(4/3), approximately **

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Self-critique (if necessary): Not sure how you did the step when you divided s by .02893 and got 34.60 s???

s / .0289 = s * ( 1 / .0289).

1 / .0289 is about 35.

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Self-critique rating #$&*: 1

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&#Your work looks good. See my notes. Let me know if you have any questions. &#