8.4 properties of logarithms
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8.4 – Properties of Logarithms
LOGARITHMIC PROPERTY DAY!!!!
Properties of Logarithms
There are four basic properties of logarithms that we will be working with. For every case, the base of the logarithm can not be equal to 1 and the values must all be positive (no negatives in logs)
Product Rule
logbMN = LogbM + logbN
Ex: logbxy = logbx + logby
Ex: log6 = log 2 + log 3
Ex: log39b = log39 + log3b
Quotient Rule
Ex:
Ex:
Ex:
yxy
x555 logloglog
P
MN2log
NMN
Mbbb logloglog
5loglog5
log 222 aa
PNM 222 logloglog
Power Rule
Ex:
Ex:
Ex:
BB 52
5 log2log
437log ba
MxM bx
b loglog
5log5log 22 xx
ba 77 log4log3
Let’s try some Working backwards now: write the following as a
single logarithm.
16log4log 44 nm 22 log4log2 2log5log
Let’s try some Write the following as a single logarithm.
16log4log 44 2log5log nm 22 log4log2
Let’s try something more complicated . . .Condense the logslog 5 + log x – log 3 + 4log 5
)xlogx(logxloglog 53525 4444
Let’s try something more complicated . . . Condense the logslog 5 + log x – log 3 + 4log 5
)xlogx(logxloglog 53525 4444
Let’s try something more complicated . . . Expand
2
4
y3
x10log
3
8 5
x2log
Let’s try something more complicated . . . Expand
2
4
y3
x10log
3
8 5
x2log