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Key equations

  • Composition of two functions
    ( g f ) ( x ) = g ( f ( x ) )
  • Absolute value function
    f ( x ) = { x , x < 0 x , x 0

For the following exercises, (a) determine the domain and the range of each relation, and (b) state whether the relation is a function.

x y x y
−3 9 1 1
−2 4 2 4
−1 1 3 9
0 0

a. Domain = { −3 , −2 , −1 , 0 , 1 , 2 , 3 } , range = { 0 , 1 , 4 , 9 } b. Yes, a function

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x y x y
−3 −2 1 1
−2 −8 2 8
−1 −1 3 −2
0 0
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x y x y
1 −3 1 1
2 −2 2 2
3 −1 3 3
0 0

a. Domain = { 0 , 1 , 2 , 3 } , range = { −3 , −2 , −1 , 0 , 1 , 2 , 3 } b. No, not a function

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x y x y
1 1 5 1
2 1 6 1
3 1 7 1
4 1
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x y x y
3 3 15 1
5 2 21 2
8 1 33 3
10 0

a. Domain = { 3 , 5 , 8 , 10 , 15 , 21 , 33 } , range = { 0 , 1 , 2 , 3 } b. Yes, a function

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x y x y
−7 11 1 −2
−2 5 3 4
−2 1 6 11
0 −1
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For the following exercises, find the values for each function, if they exist, then simplify.

a. f ( 0 ) b. f ( 1 ) c. f ( 3 ) d. f ( x ) e. f ( a ) f. f ( a + h )

f ( x ) = 5 x 2

a. −2 b. 3 c. 13 d. −5 x 2 e. 5 a 2 f. 5 a + 5 h 2

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f ( x ) = 4 x 2 3 x + 1

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f ( x ) = 2 x

a. Undefined b. 2 c. 2 3 d. 2 x e 2 a f. 2 a + h

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f ( x ) = | x 7 | + 8

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f ( x ) = 6 x + 5

a. 5 b. 11 c. 23 d. −6 x + 5 e. 6 a + 5 f. 6 a + 6 h + 5

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f ( x ) = x 2 3 x + 7

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f ( x ) = 9

a. 9 b. 9 c. 9 d. 9 e. 9 f. 9

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For the following exercises, find the domain, range, and all zeros/intercepts, if any, of the functions.

g ( x ) = 8 x 1

x 1 8 ; y 0 ; x = 1 8 ; no y -intercept

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f ( x ) = −1 + x + 2

x −2 ; y −1 ; x = −1 ; y = −1 + 2

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g ( x ) = 3 x 4

x 4 ; y 0 ; no x -intercept; y = 3 4

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g ( x ) = 7 x 5

x > 5 ; y > 0 ; no intercepts

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For the following exercises, set up a table to sketch the graph of each function using the following values: x = −3 , −2 , −1 , 0 , 1 , 2 , 3 .

f ( x ) = x 2 + 1

x y x y
−3 10 1 2
−2 5 2 5
−1 2 3 10
0 1
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f ( x ) = 3 x 6

x y x y
−3 −15 1 −3
−2 −12 2 0
−1 −9 3 3
0 −6


An image of a graph. The x axis runs from -3 to 3 and the y axis runs from -3 to 3. The graph is of the function “f(x) = 3x - 6”, which is an increasing straight line. The function has an x intercept at (2, 0) and the y intercept is not shown.

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f ( x ) = 1 2 x + 1

x y x y
−3 1 2 1 3 2
−2 0 2 2
−1 1 2 3 5 2
0 1
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f ( x ) = 2 | x |

x y x y
−3 6 1 2
−2 4 2 4
−1 2 3 6
0 0


An image of a graph. The x axis runs from -3 to 3 and the y axis runs from -2 to 6. The graph is of the function “f(x) = 2 times the absolute value of x”. The function decreases in a straight line until it hits the origin, then begins to increase in a straight line. The function x intercept and y intercept are at the origin.

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f ( x ) = x 2

x y x y
−3 −9 1 −1
−2 −4 2 −4
−1 −1 3 −9
0 0
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f ( x ) = x 3

x y x y
−3 −27 1 1
−2 −8 2 8
−1 −1 3 27
0 0


An image of a graph. The x axis runs from -3 to 3 and the y axis runs from -27 to 27. The graph is of the function “f(x) = x cubed”. The curved function increases until it hits the origin, where it levels out and then becomes even. After the origin the graph begins to increase again. The x intercept and y intercept are both at the origin.

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For the following exercises, use the vertical line test to determine whether each of the given graphs represents a function. Assume that a graph continues at both ends if it extends beyond the given grid. If the graph represents a function, then determine the following for each graph:

  1. Domain and range
  2. x -intercept, if any (estimate where necessary)
  3. y -Intercept, if any (estimate where necessary)
  4. The intervals for which the function is increasing
  5. The intervals for which the function is decreasing
  6. The intervals for which the function is constant
  7. Symmetry about any axis and/or the origin
  8. Whether the function is even, odd, or neither
An image of a graph. The x axis runs from -5 to 5 and the y axis runs from -5 to 5. The graph is of a relation that is curved. The relation decreases until it hits the point (-1, 0), then increases until it hits the point (0, 1), then decreases until it hits the point (1, 0), then increases again.

Function; a. Domain: all real numbers, range: y 0 b. x = ± 1 c. y = 1 d. −1 < x < 0 and 1 < x < e. < x < 1 and 0 < x < 1 f. Not constant g. y -axis h. Even

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An image of a graph. The x axis runs from -5 to 5 and the y axis runs from -5 to 5. The graph is of a relation that is curved. The curved relation increases the entire time. The x intercept and y intercept are both at the origin.

Function; a. Domain: all real numbers, range: −1.5 y 1.5 b. x = 0 c. y = 0 d. all real numbers e. None f. Not constant g. Origin h. Odd

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An image of a graph. The x axis runs from -5 to 5 and the y axis runs from -5 to 5. The graph is of a relation that is a horizontal line until the point (-2, -2), then it begins increasing in a straight line until the point (2, 2). After these points, the relation becomes a horizontal line again. The x intercept and y intercept are both at the origin.

Function; a. Domain: < x < , range: −2 y 2 b. x = 0 c. y = 0 d. −2 < x < 2 e. Not decreasing f. < x < 2 and 2 < x < g. Origin h. Odd

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An image of a graph. The x axis runs from -5 to 5 and the y axis runs from -5 to 5. The graph is of a relation that starts at the point (-4, 4) and is a horizontal line until the point (0, 4), then it begins decreasing in a curved line until it hits the point (4, -4), where the graph ends. The x intercept is approximately at the point (1.2, 0) and y intercept is at the point (0, 4).

Function; a. Domain: −4 x 4 , range: −4 y 4 b. x = 1.2 c. y = 4 d. Not increasing e. 0 < x < 4 f. −4 < x < 0 g. No Symmetry h. Neither

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For the following exercises, for each pair of functions, find a. f + g b. f g c. f · g d. f / g . Determine the domain of each of these new functions.

f ( x ) = 3 x + 4 , g ( x ) = x 2

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f ( x ) = x 8 , g ( x ) = 5 x 2

a. 5 x 2 + x 8 ; all real numbers b. −5 x 2 + x 8 ; all real numbers c. 5 x 3 40 x 2 ; all real numbers d. x 8 5 x 2 ; x 0

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f ( x ) = 3 x 2 + 4 x + 1 , g ( x ) = x + 1

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f ( x ) = 9 x 2 , g ( x ) = x 2 2 x 3

a. −2 x + 6 ; all real numbers b. −2 x 2 + 2 x + 12 ; all real numbers c. x 4 + 2 x 3 + 12 x 2 18 x 27 ; all real numbers d. x + 3 x + 1 ; x 1 , 3

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Source:  OpenStax, Calculus volume 1. OpenStax CNX. Feb 05, 2016 Download for free at http://cnx.org/content/col11964/1.2
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