Solving Exponential and Logarithmic Equations
A free Precalculus lesson from the “Exponential and Logarithmic Functions” unit, with a worked example and practice problems including step-by-step solutions.
Solving exponential and log equations means choosing the inverse form and checking any domain restrictions. This lesson is part of Precalculus: Advanced Functions, so the emphasis is on interpreting behavior, choosing the right representation, and explaining the result clearly rather than memorizing isolated algebra moves.
What you'll learn
- Solve equations by matching bases, rewriting logs, and checking domains
- Use solving exponential and logarithmic equations in symbolic and graph-based problems
- Check common mistakes before finalizing an answer
Why it matters: Exponential and logarithmic models describe growth, decay, sound, pH, finance, and scientific scales.
Worked example
Problem. Solve 3^x = 3^3.
- Worked Example: First identify exactly what the question is asking: Solve 3^x = 3^3.
- Use inverse operations to isolate the unknown, and keep both sides balanced at every step.
- Both sides are powers of 3, so the bases already match.
- Equal bases force equal exponents, so x = 3.
- So x = 3.
- Check the result by substituting or estimating: the response should match 3 and make sense in the original problem.
Answer: 3
Practice problems
1. Solve 3^x = 3^3.
Show solution
- Warm-up: First identify exactly what the question is asking: Solve 3^x = 3^3.
- Use inverse operations to isolate the unknown, and keep both sides balanced at every step.
- Both sides are powers of 3, so the bases already match.
- Equal bases force equal exponents, so x = 3.
- So x = 3.
- Check the result by substituting or estimating: the response should match 3 and make sense in the original problem.
Answer: 3
2. Solve 2^x = 16.
Show solution
- Warm-up: First identify exactly what the question is asking: Solve 2^x = 16.
- Use inverse operations to isolate the unknown, and keep both sides balanced at every step.
- Write 16 as a power of 2: 2^4 = 16.
- Now 2^x = 2^4, so the exponents match.
- So x = 4.
- Check the result by substituting or estimating: the response should match 4 and make sense in the original problem.
Answer: 4
3. Solve log base 3 of x = 2.
Show solution
- Core Practice: First identify exactly what the question is asking: Solve log base 3 of x = 2.
- For logarithms, rewrite the statement as an exponent question so the base, exponent, and result are clear.
- Rewrite in exponential form: 3^2 = x.
- 3^2 = 9.
- So x = 9, and 9 > 0 so it is a valid input.
- Check the result by substituting or estimating: the response should match 9 and make sense in the original problem.
Answer: 9
4. Solve 2^x = 1.
Show solution
- Core Practice: First identify exactly what the question is asking: Solve 2^x = 1.
- Use inverse operations to isolate the unknown, and keep both sides balanced at every step.
- Any nonzero base raised to the 0 power equals 1.
- So 2^x = 1 forces x = 0.
- So x = 0.
- Check the result by substituting or estimating: the response should match 0 and make sense in the original problem.
Answer: 0
5. Solve 3^x = 3.
Show solution
- Core Practice: First identify exactly what the question is asking: Solve 3^x = 3.
- Use inverse operations to isolate the unknown, and keep both sides balanced at every step.
- Write the right side as 3^1.
- Then 3^x = 3^1, so the exponents match.
- So x = 1.
- Check the result by substituting or estimating: the response should match 1 and make sense in the original problem.
Answer: 1
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