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# Help Please...3 Problems that are logarithmic??

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I just need help for these problems this morning asap if possible. :)

1.

Solve the logarithmic equation.

y=log(5) 125

y =

2.

Options

3.

x=

Please and thank you!!!!!! 0^>

Dec 14, 2018

#1
+100519
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I don't quite understand the first one, Phoenix....are we multiplying log(5) by 125???

2.

5 * 8^(4x) = 376          divide both sides by 5

8^(4x) =  376 / 5        take the log of both sides

log 8^(4x) = log (376 / 5)

Remember   that      log a^b    can be written as   b*log (a)

So

(4x) log (8)  = log (376/5)

x *(4 * log 8)   =  log (376 / 5)        divide both sides by  (4 * log 8)

x =   log (376/5) / [ 4 * log 8 ]    =  log (75.2) / (4log 8)

Dec 14, 2018
#2
+100519
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Last one

The key here is to notice that  81  =  3^4

The reason for doing this is that we won't have to use any logs to solve for x

So....we actually have

3^(7x)  =  (3^4)^(x + 9)

Remember that    (a^m)^n  =  a^(m * n)       so.....

3^(7x) =  3^(4 * (x + 9) )

Since the bases are the same, we can solve for the exponents

7x  =  4 (x + 9)     simplify

7x  = 4x + 36      subtract 4x from both sides

3x = 36    divide both sides by 3

x = 12

Dec 14, 2018
#3
+327
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Thank you much for your help CPhill...I may have worded the first question wrong on my end. I was able to complete it okay on my own. :)

PhoenixForever  Dec 14, 2018
#4
+100519
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OK......march on....!!!!

CPhill  Dec 14, 2018