Question

Devonte used the change of base formula to approximate log8 (21). Which expression did Devonte use?

Answer 1

log25/log8 should be your answer

Answer 2

`log_8(21)=(log21)/(log8)`

Explanation:

Given : Log expression
`log_8(21)`

To find : Write the expression using the change of base formula.

Solution :

Logarithmic change of base rule formula is

`log_ab=(log_eb)/(log_ea)`

Now, using logarithmic rule in
`log_8(21)`

where a=8 and b=21

`log_8(21)=(log_(10)21)/(log_(10)8)`

`log_8(21)=(log21)/(log8)`

Therefore, The expression Devonte use
`log_8(21)=(log21)/(log8)`