Evaluate log base 0.125 of 64, i.e., log_{0.125}(64). Write both the power-of-2 reduction and the final numeric value.

Difficulty: Easy

Correct Answer: - 2

Explanation:


Introduction / Context:
We evaluate a logarithm with base less than 1 by expressing base and argument as powers of a common number (2) and then using exponent division.


Given Data / Assumptions:

  • Base: 0.125 = 1/8 = 2^(−3)
  • Argument: 64 = 2^6


Concept / Approach:
Use log_{a^m}(a^n) = n/m. For a base less than 1 (negative exponent on 2), the result may be negative even with a > 1 argument.


Step-by-Step Solution:

log_{0.125}(64) = log_{2^(−3)}(2^6) = 6/(−3) = −2


Verification / Alternative check:
Check: (0.125)^(−2) = (1/8)^(−2) = 8^2 = 64, confirming the result.


Why Other Options Are Wrong:
2 has the wrong sign for a base less than 1; 0 or “can’t be determined” contradict the exact exponent check above.


Common Pitfalls:
Ignoring that a fractional base (<1) leads to negative log values for arguments >1 is a common source of sign errors.


Final Answer:
- 2

Discussion & Comments

No comments yet. Be the first to comment!
Join Discussion