Question 197197: log7 (x+3)- log7 (x-3)=1
log3 (y-8)+ log3 (y=4)= log3 13
log2 84
I need to solve these problems but have no clue how to.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! You should review the four Laws of Logarithms.
Product, Quotient, Power, Change of Base
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log7 (x+3)- log7 (x-3)=1
log7[(x+3)/(x-3)] = 1
[x+3]/[x-3] = 7
x+3 = 7x-21
6x = 24
x = 4
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log3 (y-8)+ log3 (y=4)= log3 13
log3[(y-8)(y+4)] = log3[13]
y^2-4y-32 = 13
y^2 -4y -45 = 0
etc.
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log2 84 = [log[84]/[log[2]] = 6.3923...
Cheers,
Stan H.
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