Question

Base 7= B7
Evaluate the log without a calculator
logB7 6=0.9
logB7 4=0.7
logB7 5=0.8
Find logB7 28/5

Answer 1

@mathmale

Answer 2

You want everything to solved for you. While you watch.

Answer 3

no, i just need to know how to do it

Answer 4

Base 7=B7? Is that the original question?

Answer 5

yes @Isaiah.Feynman

Answer 6

28 can be expressed as 4*7 ; 5 can be expressed as (6 + 4) / 2
when you multiply numbers add the logs
when you divide numbers subtract the logs
this should help

Answer 7

so then i put logB7 (4*7)- logB7 (6+4/2)?

Answer 8

Hello, Shay! Glad to see you again!

logB7 6=0.9
logB7 4=0.7
logB7 5=0.8
Find logB7 28/5

Here's what I'd do:

Use the rule of logs for division: log (a/b) = log a - log b.

Therefore, logB7 (28/5) = logB7 (28)-logB7 (5)

Note that logB7 (5) is given (above), but that logB7 (28) is not.

However, logB7 (28) can be written as logB7 (4) + logB7 (7).

logB7 (7) is not given above. However, if you recognize that

logB7 (7^1) = 1, the rest is easy. Note how ln e^1 = ln e = 1; log 10^5=5, and so on. Ask me if this is confusing for you.

so, now let's put everything together.

logB7 (28/5) = logB7 (4) + logB7 (7) - logB7 (5).

Please review what I've typed above and then try to arrive at a final answer. Show your work, so that I can give you suitable feedback.