Algebra II : Inverse Functions

Study concepts, example questions & explanations for Algebra II

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Example Questions

Example Question #91 : Inverse Functions

Choose the inverse of  \(\displaystyle y=\frac{x-3}{2}\) .

Possible Answers:

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

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

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

\(\displaystyle y=3x-2\)

Correct answer:

Explanation:

To find the inverse of a linear function, switch the variables and solve for y.

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

Switch the variables:

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

Multiply both sides by 2:

\(\displaystyle 2x=y-3\)

Add 3 to both sides to isolate y:

 

 

Example Question #91 : Inverse Functions

Find the inverse function:  \(\displaystyle y=2(5-x)\)

Possible Answers:

\(\displaystyle y=\frac{1}{5}x-\frac{1}{10}\)

\(\displaystyle y=\frac{1}{2}x-10\)

\(\displaystyle y=\frac{1}{2}x-\frac{1}{5}\)

\(\displaystyle y=\frac{1}{2}x-\frac{1}{10}\)

Correct answer:

Explanation:

Interchange the x and y-variables.

\(\displaystyle x=2(5-y)\)

Solve for y.  Divide by two on both sides.

\(\displaystyle \frac{x}{2}=\frac{2(5-y)}{2}\)

\(\displaystyle \frac{x}{2}=5-y\)

Add \(\displaystyle y\) on both sides.

\(\displaystyle \frac{x}{2}+y=5-y+y\)

\(\displaystyle \frac{x}{2}+y=5\)

Subtract \(\displaystyle \frac{x}{2}\) on both sides.

\(\displaystyle \frac{x}{2}+y-\frac{x}{2}=5-\frac{x}{2}\)

Simplify both sides.

The answer is:  

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