You can put this solution on YOUR website! (1/2)[ log base 5 1] - 2 [log base 5 5]
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Notes:
log(base 5) 1 = 0 because 5^0=1
log(base 5) 5 = 1 because 5^1=5
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Your problem becomes:
(1/2)*0 - 2(1)
= -2
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Cheers,
Stan H.