How do you calculate log_8 7.9log87.9 with a calculator?

1 Answer
Sep 6, 2016

log_8 7.9=0.9939log87.9=0.9939

Explanation:

Let log_ba=xlogba=x. Hence b^x=abx=a and log (to the base 1010) on both sides, we get

xlogb=logaxlogb=loga or x=loga/logbx=logalogb

Hence log_ba=loga/logblogba=logalogb and

log_8 7.9=log7.9/log8log87.9=log7.9log8

= 0.8976/0.90310.89760.9031

= 0.99390.9939