Question 482777
{{{ log(5,a) + log(5,b) - log(5,c) }}}
Make use of 2 rules
1st rule:
{{{ log(a) + log(b) = log(a*b) }}}
2nd rule:
{{{ log(a) - log(b) = log(a/b) }}}
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Using 1st rule:
{{{ log(5,a) + log(5,b) = log(5,a*b) }}}
Now I have:
{{{ log(5,a*b) - log(5,c) }}}
{{{ log(5, (a*b)/c) }}} answer
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Suppose 
{{{ a = 5 }}}
{{{ b = 25 }}}
{{{ c = 625 }}}
{{{ log(5,5) + log(5,25) = 1 + 2 }}}
{{{ 1 + 2 = 3 }}}
and
{{{ 3 - log(5,625) = 3 - 3 = 0 }}}
compare with:
{{{ log(5, (a*b)/c)  = log(5, (5*25)/635)}}}
which equals
{{{ log(5,1) }}}
The log to the base 5 which equals 1 is 0
OK