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Function Worksheets - Page 10

Function Worksheets
  • Page 10
 91.  
The function f(x) = 64x describes the distance traveled by a car in miles and x represents the time taken by the car. What is the distance traveled by the car in 3 hours?
a.
196
b.
194
c.
200
d.
192


Solution:

f(x) = 64x
[Original equation.]

f(3) = 64 x 3
[Substitute 3 for x.]

= 192
[Simplify.]

The distance traveled by the car in 3 hours is 192 miles.


Correct answer : (4)
 92.  
What is the value of the function f(3), if f(x) = 3x + 9?
a.
23
b.
24
c.
18
d.
26


Solution:

f(x) = 3x + 9
[Original equation.]

f(3) = 3(3) + 9
[Substitute 3 for x.]

= 18
[Simplify.]


Correct answer : (3)
 93.  
What is the value of the function f(6), if f(x) = 5x - 2?
a.
30
b.
28
c.
32
d.
29


Solution:

f(x) = 5x - 2
[Original equation.]

f(6) = 5(6) - 2
[Substitute 6 for x.]

= 28
[Simplify.]


Correct answer : (2)
 94.  
Kelsey bought apples at $2 each. Write a function to represent the relation between the number of apples she bought a, and the total cost, f(a).
a.
f(a) =a/2
b.
f(a) = 2/a
c.
f(a) = 2a
d.
None of the above


Solution:

The total cost = the cost of each apple x the number of apples she bought.

f(a) = $2 x a
[Substitute the values.]

f(a) = 2a
[Simplify.]

The function that represents a relation between the number of apples and the total cost is f(a) = 2a.


Correct answer : (3)
 95.  
What are the values of f(-4), f(2) and f(3.2), if f(x) = 9x2 - 2?
a.
142, 34, 90.16
b.
147, 39, 95.16
c.
152, 44, 100.16
d.
146, 38, 94.16


Solution:

f(x) = 9x2 - 2
[Original equation.]

= 142
f(-4) = 9(-4)2 - 2
[Substitute -4 for x and simplify.]

= 34
f(2) = 9(2)2 - 2
[Substitute 2 for x and simplify.]

= 90.16
f(3.2) = 9(3.2)2 - 2
[Substitute 3.2 for x and simplify.]


Correct answer : (1)
 96.  
Evaluate f(x) = 14 - 2x, for x = 1, 2, 3, 4, and find the common difference for the output.
a.
1
b.
3
c.
2
d.
None of the above


Solution:

f(x) = 14 - 2x
[Original equation.]

f(1) = 14 - 2(1)
[Substitute 1 for x.]

= 12
[Simplify.]

f(2) = 14 - 2(2)
[Substitute 2 for x.]

= 10
[Simplify.]

f(3) = 14 - 2(3)
[Substitute 3 for x.]

= 8
[Simplify.]

f(4) = 14 - 2(4)
[Substitute 4 for x.]

= 6
[Simplify.]

f(1) = 12, f(2) = 10, f(3) = 8 and f(4) = 6.

The relation between the input and the output is as input is increased by 1 output is decreased by 2.

So, the common difference is 2.


Correct answer : (3)
 97.  
Laura had $7 with her. She sold n cards at $3 each and earned some money. Identify an equation for the money she had with her finally.
a.
f(n) = 7 - n
b.
f(n) = 7n
c.
f(n) = 3n + 7
d.
f(n) = 3n - 7


Solution:

The money she had finally = money earned by selling n cards + money she had initially

The money earned by selling n cards = n × cost of each card = n × 3 = $3n

Let f(n) be the amount of money she had finally.

So, the equation for the total money she had finally is f(n) = 3n + 7


Correct answer : (3)
 98.  
Find the value of f(1), f(2), f(3) and f(4), if f(x) = 4 × 0.1x.
a.
4, 0.4, 0.04, and 0.004
b.
0.4, 0.004, 0.004, and 0.0004
c.
4, 0.04, 0.004, and 0.0004
d.
0.4, 0.04, 0.004, and 0.0004


Solution:

f(x) = 4 x 0.1x
[Original equation.]

f(1) = 4 x 0.11
[Substitute 1 for x.]

= 0.4
[Simplify.]

f(2) = 4 x 0.12
[Substitute 2 in place of x.]

= 0.04
[Simplify.]

f(3) = 4 x 0.13
[Substitute 3 in place of x.]

= 0.004
[Simplify.]

f(4) = 4 x 0.14
[Substitute 4 in place of x.]

= 0.0004
[Simplify.]

The values of f(1), f(2), f(3) and f(4) are 0.4, 0.04, 0.004 and 0.0004


Correct answer : (4)
 99.  
What are the values of f(- 4) and f(4), if f(x) = x2?
a.
16, 16
b.
-16, -16
c.
16, -16
d.
-16, 16


Solution:

f(x) = x2
[Original equation.]

f(4) = 42
[Substitute 4 for x.]

= 16
[Simplify.]

f(-4) = (-4)2
[Substitute -4 for x.]

= 16
[Simplify.]


Correct answer : (1)
 100.  
The function f(x) = 80x describes the distance traveled by a truck in miles and x represents the time taken by the truck. What is the distance traveled by the truck in 7 hours?
a.
474
b.
553
c.
560
d.
567


Solution:

f(x) = 80x
[original equation.]

f(7) = 80 x 7
[substitute 7 for x.]

= 560
[simplify.]

The distance traveled by the truck in 7 hours is 560 miles.


Correct answer : (3)

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