Question 206004
Given that log[a]5=0.8271 and log[a]20=1.5395 fing log[a]4
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Use the two facts:

1. {{{4 = 20/5}}}

2. {{{log(X,(Y/Z))=log(X,(Y))-log(X,(Z))}}}

{{{log(a,(4))}}} 

Replace {{{(4)}}} by {{{(20/5)}}}

{{{log(a,(20/5))}}}

Use 2 above with {{{X=a}}}, {{{Y=20}}}, {{{Z=5}}}

{{{log(a,(20/5))=log(a,(20))-log(a,(5))=1.5395-0.8271=0.7124}}} 

Edwin</pre>