IndietroPrecalculus Chapter 5: Inverses, Exponentials, and Logarithms – Guided Study
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Q1. Find an equation of the inverse relation for .
Background
Topic: Inverse Functions
This question tests your ability to find the inverse of a linear function by switching the roles of and and solving for $y$.
Key Terms and Formulas:
Inverse function: If is a function, its inverse undoes the action of $f(x)$.
To find the inverse, swap and and solve for $y$.
Step-by-Step Guidance
Start with the original equation: .
Switch and to get .
Solve this new equation for by isolating $y$ on one side.
Once you have by itself, write the inverse relation as
Try solving on your own before revealing the answer!
Final Answer: →
We swapped and and solved for $y$ to find the inverse relation.
Q2. Find an equation of the inverse relation for .
Background
Topic: Inverse Relations (Nonlinear)
This question asks you to find the inverse of a relation involving both and in a nonlinear way.
Key Terms and Formulas:
Inverse relation: Swap and and solve for $y$.
Be careful with exponents and algebraic manipulation.
Step-by-Step Guidance
Start with the given equation: .
Switch and to get .
Solve for in terms of by isolating $y$.
Express the inverse relation as
Try solving on your own before revealing the answer!
Final Answer: →
After swapping and solving, you get the inverse relation in terms of .
Q3. Graph as a solid line. Graph its inverse as a dashed line by reflecting across .
Background
Topic: Graphing Functions and Their Inverses
This question tests your understanding of how to graph a function and its inverse, and how the inverse is a reflection across the line .
Key Terms and Formulas:
Inverse graph: The graph of the inverse is a reflection of the original graph across the line .
To graph the inverse, swap the and coordinates of points on the original graph.
Step-by-Step Guidance
Plot the graph of as a solid curve.
Draw the line as a reference (usually a dashed diagonal line).
To graph the inverse, reflect each point on the original graph to .
Sketch the reflected (inverse) curve as a dashed line.
Try sketching the graphs before revealing the answer!
Final Answer:
The graph of is a parabola shifted up 3 units. Its inverse is not a function (unless you restrict the domain), and is the reflection of the parabola across .
Q4. Find the inverse of the function .
Background
Topic: Inverse Functions (Linear)
This question asks you to find the inverse of a simple linear function.
Key Terms and Formulas:
Inverse function: undoes the action of .
To find the inverse, swap and and solve for $y$.
Step-by-Step Guidance
Write .
Swap and to get .
Solve for by dividing both sides by 7.
Write the inverse function as
Try solving on your own before revealing the answer!
Final Answer:
The inverse function undoes the multiplication by 7 by dividing by 7.
Q5. Find the inverse of the function .
Background
Topic: Inverse Functions (Linear with Fractional Coefficient)
This question tests your ability to find the inverse of a linear function with a fractional coefficient.
Key Terms and Formulas:
Inverse function: Swap and and solve for $y$.
Be careful with fractions when isolating .
Step-by-Step Guidance
Write .
Swap and to get .
Subtract 6 from both sides to isolate the term with .
Multiply both sides by 4 to solve for .
Write the inverse function as
Try solving on your own before revealing the answer!
Final Answer:
We isolated and solved for the inverse function.
Q6. For and , use composition to show that is the inverse of .
Background
Topic: Verifying Inverses Using Composition
This question asks you to use function composition to verify that two functions are inverses.
Key Terms and Formulas:
Composition: and
If and are true inverses, both compositions should return .
Step-by-Step Guidance
Compute by substituting into .
Simplify the expression to see if it equals .
Compute by substituting into .
Simplify this expression as well.
If both simplify to , the functions are inverses.
Try working through the compositions before revealing the answer!
Final Answer:
Both and simplify to , confirming that the functions are inverses.
Q7. For and , use composition to show that is the inverse of .
Background
Topic: Verifying Inverses Using Composition (Rational Functions)
This question asks you to verify that two rational functions are inverses by using composition.
Key Terms and Formulas:
Composition: and
If both compositions return , the functions are inverses.
Step-by-Step Guidance
Compute by plugging into .
Simplify the resulting expression step by step.
Compute by plugging into .
Simplify this expression as well.
Check if both compositions simplify to .
Try working through the algebra before revealing the answer!
Final Answer:
Both compositions simplify to , confirming that the functions are inverses.