Algebra II : Linear Functions

Study concepts, example questions & explanations for Algebra II

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Example Questions

Example Question #42 : Transformations Of Linear Functions

Shift the graph \displaystyle y=9-\frac{2}{9}x three units to the left.  What's the new equation?

Possible Answers:

\displaystyle y=-\frac{2}{9}x+\frac{1}{6}

\displaystyle y=-\frac{2}{9}x+\frac{25}{3}

\displaystyle y=-\frac{2}{9}x+\frac{29}{3}

\displaystyle y=-\frac{2}{9}x+3

\displaystyle y=-\frac{2}{9}x+\frac{31}{3}

Correct answer:

\displaystyle y=-\frac{2}{9}x+\frac{25}{3}

Explanation:

In order to shift an equation to the left three units, the x-variable will need to be replaced with the quantity of \displaystyle (x+3).  This shifts all points left three units.

\displaystyle y=9-\frac{2}{9}(x+3)

Simplify the equation.

\displaystyle y=9-\frac{2}{9}x-\frac{2}{3} = \frac{27}{3}-\frac{2}{9}x-\frac{2}{3}

The answer is:  \displaystyle y=-\frac{2}{9}x+\frac{25}{3}

Example Question #43 : Transformations Of Linear Functions

Shift the line \displaystyle y=9(2x-1) up six units.  What is the new equation?

Possible Answers:

\displaystyle y= 18x+6

\displaystyle y= 18x-3

\displaystyle y= 18x-8

\displaystyle y= 18x-15

\displaystyle y= 18x+11

Correct answer:

\displaystyle y= 18x-3

Explanation:

Add six to the equation since a vertical shift will increase the y-intercept by six units.

\displaystyle y=9(2x-1)+6

Simplify this equation by distribution.

\displaystyle y=9(2x)-9(1)+6 = 18x-3

The answer is:  \displaystyle y= 18x-3

Example Question #91 : Linear Functions

Translate the function:  \displaystyle 3y=4-x to the left 5 units.  What is the equation in slope-intercept format?

Possible Answers:

\displaystyle y= -\frac{1}{3}x+\frac{1}{3}

\displaystyle y= -\frac{1}{3}x-\frac{8}{3}

\displaystyle y= -\frac{1}{3}x+\frac{8}{3}

\displaystyle y= -\frac{1}{3}x-\frac{1}{3}

\displaystyle y= -\frac{1}{3}x+3

Correct answer:

\displaystyle y= -\frac{1}{3}x-\frac{1}{3}

Explanation:

Divide by three on both sides.

\displaystyle \frac{3y}{3}=\frac{4-x}{3}

The equation becomes:  \displaystyle y=-\frac{1}{3}x+\frac{4}{3}

If this equation shifts to the left five units, we will need to replace the x term with the quantity \displaystyle (x+5).

\displaystyle y=-\frac{1}{3}(x+5)+\frac{4}{3}

Simplify this equation by distribution.

\displaystyle y=-\frac{1}{3}(x+5)+\frac{4}{3} = -\frac{1}{3}x-\frac{5}{3}+\frac{4}{3}

Combine like-terms.

The answer is:  \displaystyle y= -\frac{1}{3}x-\frac{1}{3}

Example Question #45 : Transformations Of Linear Functions

Translate the function \displaystyle y=3x-15 to the left four units.  What is the new equation?

Possible Answers:

\displaystyle y=3x-12

\displaystyle y=3x+3

\displaystyle y=3x-8

\displaystyle y=3x-3

\displaystyle y=3x-6

Correct answer:

\displaystyle y=3x-3

Explanation:

Translation of a graph to the left four units will require replacing the x-variable with the quantity:

\displaystyle (x+4)

Replace the term inside the equation.

\displaystyle y=3(x+4)-15

Use distribution so simplify the terms.

\displaystyle y=3x+12-15

Simplify the equation.

The answer is:  \displaystyle y=3x-3

Example Question #46 : Transformations Of Linear Functions

Shift the equation \displaystyle x+3y=17 up two units.   What is the new equation?

Possible Answers:

\displaystyle y= -\frac{1}{3}x+\frac{23}{3}

\displaystyle y= -\frac{1}{3}x-8

\displaystyle y=-\frac{1}{3}x+6

\displaystyle y=-\frac{1}{3}x-14

\displaystyle y= -\frac{1}{3}x-2

Correct answer:

\displaystyle y= -\frac{1}{3}x+\frac{23}{3}

Explanation:

In order to find the equation after the translation, we will need to put the equation in slope-intercept format, \displaystyle y=mx+b.

Subtract \displaystyle x from both sides of the equation.

\displaystyle x+3y-x=17-x

The equation becomes:  \displaystyle 3y= -x+17

Divide by three on both sides.

\displaystyle \frac{3y}{3}= \frac{-x+17}{3}

\displaystyle y=-\frac{1}{3}x +\frac{17}{3}

Add two to the y-intercept for the vertical shift.  This is the same as adding \displaystyle \frac{6}{3}.

\displaystyle y=-\frac{1}{3}x +\frac{17}{3}+\frac{6}{3} = -\frac{1}{3}x+\frac{23}{3}

The equation is:  \displaystyle y= -\frac{1}{3}x+\frac{23}{3}

Example Question #47 : Transformations Of Linear Functions

If the graph \displaystyle x+y=-9 is translated 5 units left, what is the new equation?

Possible Answers:

\displaystyle y=-x+5

\displaystyle y=-x+19

\displaystyle y=-x-5

\displaystyle y=-x+14

\displaystyle y=-x-14

Correct answer:

\displaystyle y=-x-14

Explanation:

Rewrite the given equation in standard form to slope intercept format, \displaystyle y=mx+b.

Subtract x from both sides.

\displaystyle x+y-x=-9-x

The slope intercept form is:  \displaystyle y=-x-9

If the line is translated 5 units to the left, we need to replace the quantity of x with \displaystyle (x+5).

\displaystyle y=-(x+5)-9

Simplify the equation.  Distribute the negative through the binomial.

\displaystyle y=-(x+5)-9 = -x-5-9 =-x-14

The answer is:  \displaystyle y=-x-14

Example Question #48 : Transformations Of Linear Functions

Shift the graph \displaystyle 2y-3x=4 down four units.  What is the new equation?

Possible Answers:

\displaystyle y=\frac{3}{2}x-1

\displaystyle y=\frac{3}{2}x-5

\displaystyle y=\frac{3}{2}x

\displaystyle y=\frac{3}{2}x+1

\displaystyle y=\frac{3}{2}x-2

Correct answer:

\displaystyle y=\frac{3}{2}x-2

Explanation:

Rewrite this equation in slope intercept form \displaystyle y=mx+b.

Add \displaystyle 3x on both sides.

\displaystyle 2y-3x+3x=4+3x

The equation becomes:

\displaystyle 2y = 3x+4

Divide by two on both sides.

\displaystyle \frac{2y }{2}= \frac{3x+4}{2}

The equation in slope intercept form is:  \displaystyle y=\frac{3}{2}x+2

Shifting this equation down four units means that the y-intercept will be decreased four units.

The answer is:  \displaystyle y=\frac{3}{2}x-2

Example Question #49 : Transformations Of Linear Functions

Shift the line \displaystyle x=3y+1 left three units.  What is the new equation?

Possible Answers:

\displaystyle y= \frac{1}{3}x+\frac{2}{3}

\displaystyle y= \frac{1}{3}x-\frac{4}{3}

\displaystyle y= \frac{2}{3}x-\frac{1}{3}

\displaystyle y= \frac{2}{3}x-\frac{2}{3}

\displaystyle y= \frac{1}{3}x+\frac{4}{3}

Correct answer:

\displaystyle y= \frac{1}{3}x+\frac{2}{3}

Explanation:

Rewrite the equation \displaystyle x=3y+1 in slope-intercept form:   \displaystyle y=mx+b

Subtract one from both sides.

\displaystyle x-1=3y+1-1

\displaystyle x-1=3y

Divide by three on both sides.

\displaystyle \frac{x-1}{3}=\frac{3y}{3}

\displaystyle y=\frac{1}{3}x-\frac{1}{3}

If this line is shifted to the left three units, replace the x-variable with \displaystyle (x+3).

\displaystyle y=\frac{1}{3}(x+3)-\frac{1}{3}

Simplify by distribution.

\displaystyle y=\frac{1}{3}x+1-\frac{1}{3} = \frac{1}{3}x+\frac{2}{3}

The answer is:  \displaystyle y= \frac{1}{3}x+\frac{2}{3}

Example Question #92 : Linear Functions

Shift the equation \displaystyle y=-\frac{1}{3}x-1 to the left two units.  What is the new equation?

Possible Answers:

\displaystyle y=-\frac{1}{3}x+\frac{1}{3}

\displaystyle y=-\frac{1}{3}x+\frac{2}{3}

\displaystyle y=-\frac{1}{3}x-\frac{2}{3}

\displaystyle y=-\frac{1}{3}x-\frac{5}{3}

\displaystyle y=-\frac{1}{3}x-\frac{1}{3}

Correct answer:

\displaystyle y=-\frac{1}{3}x-\frac{5}{3}

Explanation:

If the linear function is shifted left two units, the x-variable must be replaced with the quantity of \displaystyle (x+2).

\displaystyle y=-\frac{1}{3}(x+2)-1

Simplify the equation by distribution.

\displaystyle y=-\frac{1}{3}x-\frac{2}{3}-1= -\frac{1}{3}x-\frac{2}{3}-\frac{3}{3}

Combine like terms.

The answer is:  \displaystyle y=-\frac{1}{3}x-\frac{5}{3}

Example Question #381 : Functions And Graphs

Translate the equation \displaystyle y=-3x-8 left four units.  What is the new equation?

Possible Answers:

\displaystyle y= -3x-12

\displaystyle y= -3x+20

\displaystyle y= -3x+12

\displaystyle y= -3x-20

\displaystyle y= -3x+4

Correct answer:

\displaystyle y= -3x-20

Explanation:

To shift the line left four units, we will need to replace the x-variable with the quantity of:

\displaystyle (x+4)

Replace this term in the original equation.

\displaystyle y=-3(x+4)-8

Use distribution to simplify.

\displaystyle y=-3x-12-8 = -3x-20

The answer is:  \displaystyle y= -3x-20

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