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3^3/3^y=1/9 Can you help me solve for y?

 Jan 8, 2016
 #1
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Solve for y over the real numbers:
3^(3-y) = 1/9

Take reciporicals of both sides:
3^(y-3) = 9

Multiply both sides by 27:
3^y = 243

243 = 3^5:
3^y = 3^5

Equate exponents of 3 on both sides:
Answer: | y = 5

 Jan 8, 2016
 #2
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Sure !

3^3 = 27 in the numerator so you have:

 

27/3^y = 1/9   multiply both sides by 9

243/3^y = 1     Now multiply both sides by 3^y

243=3^y         Now take the log of both sides

 

log 243 =  log (3^y) = y log 3    Now divide both sides by log 3

 

log 243  /  log 3  = y       NOw use the calculator   to find y = 5

 Jan 8, 2016
edited by Guest  Jan 8, 2016
 #3
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5  it is

 Jan 8, 2016
edited by Guest  Jan 8, 2016

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