Exercise 9 Page 124

Example 2 provides the number of miles a helicopter travels on various trips. To begin, we will draw the graph given in the example.

The graph above shows the distance traveled for the first flight. We can see that this flight took 3 hours because the distance to the destination is 0 when x=3. We are also given the function for the second flight. f(x)=250-75x

To graph this function we will make a table of values.

x	250 - 75x	f(x)
0	250 - 75( 0)	250
1	250 - 75( 1)	175
2	250 - 75( 2)	100
3	250 - 75( 3)	25
4	250 - 75( 4)	-50

Now we will plot the found ordered pairs.

Let's draw a line through the points. Note that the function only makes sense when x and f(x) are positive.

From the graph of the second flight, we can see that when f(x)=0, x>3. Therefore, the first flight takes less time. To check this answer we can substitute f(x)=0 into the equation and solve for x.

f(x)=250-75x

Substitute

f(x)= 0

0=250-75x

AddEqn

LHS+75x=RHS+75x

75x=250

DivEqn

.LHS /75.=.RHS /75.

x=3.33

The second flight takes 3.33 hours. Therefore, we confirmed that the first flight takes less time.