Question

Does anyone know what is a simplified form of the expression log21(5) +log21(4) -log21(2)?

All I know is that the answer is log21 (10), but I don't know how to get that answer.

Answer 1

use below :-
\(\log a + \log b = \log (ab)\)

\(\log a - \log b = \log (a/b)\)

Answer 2

wait, is log a log 21(5) and log b log 21(4)?

Answer 3

\(\log_{21}(5) +\log_{21}(4) -\log_{21}(2)\)

Answer 4

\(\log_{21}(5\times 4) -\log_{21}(2)\)

Answer 5

\(\log_{21}(5\times 4/2)\)

Answer 6

\(\log_{21}(20/2)\)

Answer 7

\(\log_{21}(10)\)

Answer 8

oh ok, thank-you

Answer 9

so, do we always use that formula to solve a problem like that?

Answer 10

yes, u can always use that formula as long u have the same base...

Answer 11

base is 21 for our current problem

Answer 12

oh, ok thank-you

Answer 13

again

Answer 14

np :)