MA141 w1journal

2. The resistance y (in ohms) of 1000 feet of copper wire at 68 degrees Fahrenheit is given by the function   , where x is the diameter of the wire in thousandths of an inch.

a. Fill in the table:

b. Use the table above to estimate the resistance when x = 45.5 and for x = 75.5. Using the table above when x = 45.5 the estimated resistance would be about 5. When x = 75.5 the estimated resistance would be about 1.9 = (x-)

x = 45.4

=4.1480 + 0.23333 x 5.5

=5.431315 = 5.4313

x=75.5 ,

y=1.6203 + 2.1163 + (75.5-70)

=1.6203 + 0.0496x5.5

=1.6203 + 0.2728 = 1.8931

c. Compare your answers in part b with the values calculated by using the function. y=

x=45.4 , y = = 5.0091

x= 75.5 , y = = 1.8192

d. What can you conclude about the relationship between the diameter of the copper wire and the resistance? The bigger the diameters the less resistance the copper will have

3. A school purchases a printer for $24,000. It has a 10 year life expectancy. Its value at that time is expected to be $2000. Write a linear equation giving the value V of the equipment during the 10 years it will be in use.

Line equation in the form of y=mx+c

m=

m = -2200

c= 2400 initial value

v- -2200 x+2400

4. A manufacturer of games notes that the variable cost for producing a game is $0.90 per unit and the fixed costs are $6000. Each game sells for $1.65. If x is the number of games produced. Determine the following:

a. Express the total cost C as a function of the number of games produced. The total cost C as a function x

C= 0.90 x+6000

b. Write the average cost per unit as a function of x C= C= 0.90 +

5. Use the graph of the function to answer parts (a)–(d).

a. Find the domain and range of f. domain : [-4,5)

range : [0,9)

b. Find the zero(s) of f. zero : 3

c. Determine the open intervals on which f is increasing, decreasing, or constant. increasing : (-4,0) U (3,5) decreasing : (0, 3)

d. Approximate any relative minimum or relative maximum values of f.

maximum : (0,9)

minimum : (3,0)