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C H A P T E R 2 Polynomial and Rational Functions

C H A P T E R 2 Polynomial and Rational Functions

C H A P T E R 2 Polynomial and Rational Functions

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Problem Solving for Chapter 2 261<br />

12. (a)<br />

(b)<br />

50<br />

1<br />

y <br />

0.007x 0.44<br />

0<br />

0<br />

70<br />

1<br />

y 0.0313x<br />

0.007x 0.44<br />

y 2 Age, x Near point, y<br />

50 (c)<br />

Age, x<br />

Near point, y Quadratic <strong>Rational</strong><br />

16 3.0<br />

Model Model<br />

32<br />

44<br />

4.7<br />

9.8<br />

0<br />

0<br />

70<br />

16<br />

32<br />

3.0<br />

4.7<br />

3.66<br />

2.32<br />

3.05<br />

4.63<br />

50 19.7<br />

44 9.8 11.83 7.58<br />

60 39.4<br />

50 19.7 19.97 11.11<br />

60 39.4 38.54 50.00<br />

1.586x 21.02<br />

The models are fairly good fits to the data. The quadratic<br />

model seems to be a better fit for older ages <strong>and</strong> the<br />

rational model a better fit for younger ages.<br />

(d) For x 25, the quadratic model yields y 0.9325 inches<br />

<strong>and</strong> the rational model yields y 3.774 inches.<br />

(e) The reciprocal model cannot be used to predict the near<br />

point for a person who is 70 years old because it results in<br />

a negative value y 20. The quadratic model yields<br />

y 63.37 inches.

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