Solve log₇5 - log₇2: Base 7 Logarithm Subtraction

Question

log75log72= \log_75-\log_72=

Video Solution

Solution Steps

00:00 Solve
00:09 We will use the formula for subtracting logarithms
00:17 Subtracting logarithms equals the logarithm of the quotient of numbers
00:24 We will use this formula in our exercise
00:34 And this is the solution to the question

Step-by-Step Solution

To solve the problem, let's use the rules of logarithms:

  • Step 1: Recognize that we are dealing with the subtraction of logarithms sharing the same base, which calls for the identity logbMlogbN=logb(MN)\log_b M - \log_b N = \log_b \left(\frac{M}{N}\right).
  • Step 2: Apply this identity to the expression log75log72\log_7 5 - \log_7 2.
  • Step 3: Realize that this can thus be expressed as a single logarithm: log7(52)\log_7 \left(\frac{5}{2}\right).
  • Step 4: Simplify the fraction, yielding log72.5\log_7 2.5.

Therefore, the simplification results in the expression: log72.5\log_7 2.5.

This matches the correct answer from the given choices.

Answer

log72.5 \log_72.5


Related Subjects