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Solution. We simply evaluate

1 3
" # " #
h 1 = h
2 2
3
" # 2
= −16 +100
2
−16(9)
= +100
4
= −36 + 100
=64.

1
After 1 seconds, the object is 64 feet above the ground.
2

It is hard to resist asking: how long until the object hits the ground? In function terms, the question
is: for what value of t is it true that h(t) = 0? See if you can figure it out.

6.3.1 Exercises

For the function f (x)= 2x − 5, find:

1. f (−2)

2. f (0)

1
3. f ( )
2
4. f (0.75)

2
For the function g(t)= −2t +4t +1, find:
5. g(−3)

6. g(0)

7. g(1)

2
8. g( )
3

−2
9. g( )
3
10. In 1960, New York City Taxis were much cheaper. The initial charge was $0.25, after that, a charge
of $0.05 per 1 mile, and no charge for sitting in traffic. Write a linear function which expresses
5
how the taxi fare depended on the distance travelled in 1960. Compare the price of a 10 mile ride
today, and a 10-mile ride in 1960.

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