Algebra II : Inverse Functions

Study concepts, example questions & explanations for Algebra II

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Example Questions

Example Question #761 : Algebra Ii

Determine the inverse of:  \displaystyle y=9(6x-2)

Possible Answers:

\displaystyle y=-\frac{1}{54}x+\frac{1}{3}

\displaystyle y=\frac{1}{54}x+18

\displaystyle y=\frac{1}{54}x+\frac{1}{3}

\displaystyle y=-\frac{1}{54}x+18

\displaystyle y=\frac{1}{54}x+3

Correct answer:

\displaystyle y=\frac{1}{54}x+\frac{1}{3}

Explanation:

Interchange the x and y-variables and solve for y.

\displaystyle x=9(6y-2)

Distribute the nine through the binomial.

\displaystyle x=9(6y)+9(-2) = 54y-18

\displaystyle x= 54y-18

Add eighteen on both sides.

\displaystyle x+(18)= 54y-18+(18)

\displaystyle x+18=54y

Divide by 54 on both sides.

\displaystyle \frac{x+18}{54}=\frac{54y}{54}

The answer is:  \displaystyle y=\frac{1}{54}x+\frac{1}{3}

Example Question #762 : Algebra Ii

Determine the inverse of \displaystyle y=2(9-2x).

Possible Answers:

\displaystyle y=-\frac{1}{4}x-18

\displaystyle y=-\frac{1}{4}x+18

\displaystyle y=-\frac{1}{4}x+\frac{9}{2}

\displaystyle y=-\frac{1}{4}x+9

\displaystyle y=\frac{1}{4}x+9

Correct answer:

\displaystyle y=-\frac{1}{4}x+\frac{9}{2}

Explanation:

Interchange the x and y-variables and solve for y.

\displaystyle x=2(9-2y)

Distribute the integer through the binomial.

\displaystyle x=2(9-2y) = 18-4y

\displaystyle x= 18-4y

Add \displaystyle 4y on both sides.

\displaystyle x+(4y)= 18-4y+(4y)

\displaystyle x+4y=18

Subtract \displaystyle x on both sides.

\displaystyle 4y=-x+18

Divide by four on both sides.

\displaystyle \frac{4y}{4}=\frac{-x+18}{4}

Simplify both sides.

The inverse is:  \displaystyle y=-\frac{1}{4}x+\frac{9}{2}

Example Question #41 : Inverse Functions

Determine the inverse of:  \displaystyle y=-3x-20

Possible Answers:

\displaystyle y=-\frac{1}{3}x+\frac{10}{3}

\displaystyle y=3x+\frac{10}{3}

\displaystyle y=\frac{1}{3}x-\frac{20}{3}

\displaystyle y=-\frac{1}{3}x+\frac{20}{3}

\displaystyle y=-\frac{1}{3}x-\frac{20}{3}

Correct answer:

\displaystyle y=-\frac{1}{3}x-\frac{20}{3}

Explanation:

Interchange the x and y-variable.

\displaystyle x=-3y-20

Add twenty on both sides.

\displaystyle x+20=-3y-20+20

\displaystyle x+20=-3y

Divide both sides by negative three.

\displaystyle \frac{x+20}{-3}=\frac{-3y}{-3}

Simplify both sides of the equation.

The answer is:  \displaystyle y=-\frac{1}{3}x-\frac{20}{3}

Example Question #762 : Algebra Ii

Determine the inverse of \displaystyle y=-9x-5

Possible Answers:

\displaystyle y= -\frac{1}{9}x+\frac{5}{9}

\displaystyle y= 9x+\frac{5}{9}

\displaystyle y= -\frac{1}{9}x-\frac{5}{9}

\displaystyle y= -\frac{1}{9}x-\frac{9}{5}

\displaystyle y= -9x+\frac{5}{9}

Correct answer:

\displaystyle y= -\frac{1}{9}x-\frac{5}{9}

Explanation:

Interchange the x and y-values.

\displaystyle x=-9y-5

Solve for y.  Add five on both sides.

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

The equation becomes:  \displaystyle x+5 =-9y

Divide by negative nine on both sides.

\displaystyle \frac{x+5}{-9} =\frac{-9y}{-9}

The answer is:  \displaystyle y= -\frac{1}{9}x-\frac{5}{9}

Example Question #763 : Algebra Ii

Determine the inverse:  \displaystyle y=3(x-10)

Possible Answers:

\displaystyle y=\frac{1}{3}x+10

\displaystyle y=-\frac{1}{3}x-10

\displaystyle y=\frac{1}{3}x-10

\displaystyle y=\frac{1}{3}x+30

\displaystyle y=-\frac{1}{3}x+30

Correct answer:

\displaystyle y=\frac{1}{3}x+10

Explanation:

Interchange both the x and y- variables.

\displaystyle x=3(y-10)

Solve for y.  Distribute the three through both terms of the binomial.

\displaystyle x=3y-30

Add 30 on both sides.

\displaystyle x+30=3y-30+30

\displaystyle x+30=3y

Divide by three on both sides.

\displaystyle \frac{x+30}{3}=\frac{3y}{3}

Simplify both sides.

The answer is:  \displaystyle y=\frac{1}{3}x+10

Example Question #764 : Algebra Ii

Determine the inverse function:  \displaystyle y=9x+26

Possible Answers:

\displaystyle y=\frac{1}{9}x-\frac{1}{3}

\displaystyle y=\frac{1}{9}x-3

\displaystyle y=-\frac{1}{9}x+\frac{26}{9}

\displaystyle y=\frac{1}{9}x-\frac{26}{9}

\displaystyle y=-9x-\frac{26}{9}

Correct answer:

\displaystyle y=\frac{1}{9}x-\frac{26}{9}

Explanation:

Interchange the x and y-variables.

\displaystyle x=9y+26

Solve for y.  Subtract 26 from both sides.

\displaystyle x-26=9y+26-26

The equation becomes:

\displaystyle x-26=9y

Divide by nine on both sides.

\displaystyle \frac{x-26}{9}=\frac{9y}{9}

Simplify both fractions.

The answer is:  \displaystyle y=\frac{1}{9}x-\frac{26}{9}

Example Question #765 : Algebra Ii

Determine the inverse of:  \displaystyle y= 7x-4

Possible Answers:

\displaystyle y=-7x+4

\displaystyle y=-7x+\frac{4}{7}

\displaystyle y=\frac{1}{7}x-\frac{4}{7}

\displaystyle y=\frac{1}{7}x+\frac{4}{7}

\displaystyle y=\frac{4}{7}x-\frac{4}{7}

Correct answer:

\displaystyle y=\frac{1}{7}x+\frac{4}{7}

Explanation:

Interchange the x and y variables and solve for y.

\displaystyle x= 7y-4

Add four on both sides.

\displaystyle x+4= 7y-4+4

Simplify both sides.

\displaystyle x+4= 7y

Divide by seven on both sides.

\displaystyle \frac{x+4}{7}= \frac{7y}{7}

The answer is:  \displaystyle y=\frac{1}{7}x+\frac{4}{7}

Example Question #766 : Algebra Ii

Determine the inverse of:  \displaystyle y=-(x+6)

Possible Answers:

\displaystyle y=x-6

\displaystyle y=-x-6

\displaystyle y=x+6

\displaystyle y=-x+6

\displaystyle y=-6x

Correct answer:

\displaystyle y=-x-6

Explanation:

In order to determine the inverse, interchange the x and y-variables.

\displaystyle x=-(y+6)

Divide by negative one on both sides.

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

Simplify both sides.

\displaystyle -x = y+6

Subtract six from both sides.

\displaystyle -x-6 = y+6-6

The answer is:  \displaystyle y=-x-6

Example Question #49 : Inverse Functions

Determine the inverse of:  \displaystyle y= 2x-50

Possible Answers:

\displaystyle y=\frac{1}{2}x-25

\displaystyle y=\frac{1}{2}x+25

\displaystyle y=-\frac{1}{2}x-50

\displaystyle y=-\frac{1}{2}x-25

\displaystyle y=-2x-50

Correct answer:

\displaystyle y=\frac{1}{2}x+25

Explanation:

Interchange the x and y-variables.

\displaystyle x= 2y-50

Add 50 on both sides.

\displaystyle x+50= 2y-50+50

The equation becomes: 

\displaystyle x+50= 2y

Divide both sides by two and split the fraction.

\displaystyle \frac{x+50}{2}=\frac{ 2y}{2}

The answer is:  \displaystyle y=\frac{1}{2}x+25

Example Question #41 : Inverse Functions

Determine the inverse:  \displaystyle y=-4x-19

Possible Answers:

\displaystyle -\frac{1}{4}x-\frac{19}{4}

\displaystyle 4x-\frac{19}{4}

\displaystyle -\frac{1}{4}x-19

\displaystyle \frac{1}{4}x-\frac{4}{19}

\displaystyle -\frac{1}{4}x+\frac{19}{4}

Correct answer:

\displaystyle -\frac{1}{4}x-\frac{19}{4}

Explanation:

Interchange the x and y-variables.

\displaystyle x=-4y-19

Add 19 on both sides.

\displaystyle x+19=-4y-19+19

\displaystyle x+19=-4y

Divide by negative four on both sides.

\displaystyle \frac{x+19}{-4}=\frac{-4y}{-4}

Simplify both sides.

The answer is:  \displaystyle -\frac{1}{4}x-\frac{19}{4}

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