BackPrecalculus Free-Response Practice: Exponential, Logarithmic, and Trigonometric Equations
Study Guide - Smart Notes
Tailored notes based on your materials, expanded with key definitions, examples, and context.
Q1. Solve for :
Background
Topic: Exponential Equations
This question tests your ability to solve exponential equations by expressing both sides with the same base and then equating exponents.
Key Terms and Formulas:
Exponential equation: An equation in which variables appear as exponents.
Properties of exponents: (if and )
Step-by-Step Guidance
Express both $27 as powers of $3$.
Rewrite the equation using these powers so both sides have base $3$.
Apply the property of exponents to set the exponents equal to each other.
Solve the resulting linear equation for .
Try solving on your own before revealing the answer!
Q2. Solve for :
Background
Topic: Exponential Equations
This question involves solving an exponential equation where the bases are different. You'll need to use logarithms to solve for .
Key Terms and Formulas:
Logarithm: is the exponent to which must be raised to get .
Logarithmic property:
Step-by-Step Guidance
Take the natural logarithm (or common logarithm) of both sides of the equation.
Use the property to bring exponents down in front.
Expand and collect like terms involving on one side of the equation.
Isolate by factoring and dividing as needed.
Try solving on your own before revealing the answer!
Q3. Solve for :
Background
Topic: Exponential Equations
This question tests your ability to manipulate exponential expressions and solve for the variable.
Key Terms and Formulas:
Exponential properties:
Step-by-Step Guidance
Rewrite as .
Factor from both terms on the left side.
Set up the resulting equation and solve for .
Take the logarithm of both sides to solve for .
Try solving on your own before revealing the answer!
Q4. Solve for :
Background
Topic: Exponential Equations (Quadratic in form)
This equation is quadratic in terms of . You'll use substitution to solve it.
Key Terms and Formulas:
Let , then
Quadratic equation:
Step-by-Step Guidance
Let and rewrite the equation in terms of .
Solve the quadratic equation for .
Set equal to each solution for .
Take the natural logarithm of both sides to solve for .
Try solving on your own before revealing the answer!
Q5. Solve for :
Background
Topic: Logarithmic Equations
This question tests your ability to use properties of logarithms to combine and solve equations, and to check for extraneous solutions.
Key Terms and Formulas:
Logarithm product rule:
Definition:
Step-by-Step Guidance
Combine the two logarithms on the left using the product rule.
Set the arguments equal by using the property that if , then (assuming ).
Solve the resulting quadratic equation for .
Check all solutions in the original equation to ensure they are valid (no negative or zero arguments in the logs).
Try solving on your own before revealing the answer!
Q6. Solve for :
Background
Topic: Logarithmic Equations
This question involves using properties of natural logarithms to solve for and checking for extraneous solutions.
Key Terms and Formulas:
Logarithm quotient rule:
Definition:
Step-by-Step Guidance
Combine the logarithms on the left using the quotient rule.
Set the arguments equal by exponentiating both sides.
Solve the resulting equation for .
Check your solution in the original equation to ensure all logarithms are defined.
Try solving on your own before revealing the answer!
Q7. Solve for :
Background
Topic: Logarithmic Equations
This question tests your ability to combine logarithms and solve for , and to check for extraneous solutions.
Key Terms and Formulas:
Logarithm product rule:
Definition:
Step-by-Step Guidance
Combine the two logarithms on the left using the product rule.
Rewrite the equation in exponential form to solve for .
Solve the resulting quadratic equation for .
Check all solutions in the original equation to ensure they are valid (no negative or zero arguments in the logs).
Try solving on your own before revealing the answer!
Q8. If and is in Quadrant II, find and .
Background
Topic: Evaluating Trigonometric Functions
This question tests your understanding of reference triangles, the Pythagorean identity, and the signs of trigonometric functions in different quadrants.
Key Terms and Formulas:
Pythagorean identity:
Signs in Quadrant II: , ,
Step-by-Step Guidance
Use the Pythagorean identity to solve for .
Determine the correct sign for based on the quadrant.
Calculate using the values of and .
Try solving on your own before revealing the answer!
Q9. If and is in Quadrant III, find and .
Background
Topic: Evaluating Trigonometric Functions
This question tests your ability to use the Pythagorean identity and quadrant information to find other trigonometric values.
Key Terms and Formulas:
Pythagorean identity:
Signs in Quadrant III: , ,
Step-by-Step Guidance
Use the Pythagorean identity to solve for .
Determine the correct sign for based on the quadrant.
Calculate as the reciprocal of .
Try solving on your own before revealing the answer!
Q10. If and is in Quadrant I, find and .
Background
Topic: Evaluating Trigonometric Functions
This question tests your ability to use right triangle relationships and trigonometric identities to find other function values.
Key Terms and Formulas:
Pythagorean theorem:
Step-by-Step Guidance
Draw a right triangle representing and label the sides.
Use the Pythagorean theorem to find the hypotenuse.
Calculate using the side lengths.
Find and then as its reciprocal.