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 #1
avatar+9468 
+2
Feb 7, 2018
 #1
avatar+9468 
+4

1.    Here's a graph of the points to get an idea of what the function looks like.

 

average rate of change   =   \(\frac{\text{change in }f(x)}{\text{change in }x}\)

 

 

average rate of change over the interval  [-6, -4]   =   \( \frac{ f(-6) \,-\, f(-4)}{ (-6) \,-\,( -4) }\)

 

\( \frac{ f(-6) \,-\, f(-4)}{ (-6) \,-\,( -4) }\,=\,\frac{ (-0.0046) \,-\, (-0.0154) }{ (-6) \,-\, (-4) }\,=\,\frac{ 0.0108 }{-2 }\,=\,- 0.0054\)

 

average rate of change over the interval  [-6, -4]   =   - 0.0054

 

Notice that this is just the slope of the line through the points  ( -6, f(-6) )  and  ( -4, f(-4) ) .

 

 

average rate of change over the interval  [-3, -1]   =   \( \frac{ f(-3) \,-\, f(-1)}{ (-3) \,-\,( -1) }\)

 

\( \frac{ f(-3) \,-\, f(-1)}{ (-3) \,-\,( -1) }\,=\, \frac{ (-0.0357) \,-\, (-0.5)}{ (-3) \,-\,( -1) }\,=\, \frac{0.4643}{ -2 }\,=\,- 0.23215\)

 

average rate of change over the interval  [-3, -1]   =   - 0.23215

 

 

How much greater is  - 0.0054  than  - 0.23215  ?

 

(-0.0054)  -  (-0.23215)   =   0.22675

Feb 5, 2018
 #1
avatar+9468 
+1

If 1 pound of apples costs  5  dollars, then 2 pounds of apples costs  5 + 5   dollars, or  2 * 5  dollars.

 

If 1 pound of apples costs  A  dollars, then 7 pounds of apples costs  7A  dollars.

If 1 pound of grapes costs  G  dollars, then 3 pounds of grapes costs  3G   dollars.

 

7 pounds of apples and 3 pounds of grapes cost 15.18 dollars.

7A  +  3G   =   15.18

                                    Let's solve this equation for  G . Subtract  7A  from both sides.

3G   =   15.18 - 7A

                                    Divide through by  3 .

G   =   5.06  -  7A/3

 

5 pounds of apples and 5 pounds of grapes costs 16.50 dollars.

5A  +  5G   =   16.50

                                                    Substitute  5.06 - 7A/3  in for  G .

5A  +  5(5.06 - 7A/3)   =   16.50

                                                    Distribute the  5  to the terms in parenthesees.

5A + 25.3 - 35A/3   =   16.50

                                                    Subtract  25.3  from both sides of the equation.

5A - 35A/3   =   -8.8

 

A(5 - 35/3)   =   -8.8

 

A( -20/3 )  =  -8.8

                                                    Multiply both sides of the equation by  -3/20 .

A   =   1.32

 

Use this value for  A  to find  G .

G   =   5.06  -  7(1.32)/3

G   =   1.98

Feb 4, 2018