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 if 3 = k * 2^r and 15 = k*4^r then what is r

 Aug 7, 2020
 #1
avatar+27644 
+1

3 = k 2^r       and 15 = k 2^2r

Multiply first equation by 5

 

5 k 2^r  = k 2^2r     divide out k

 

5 * 2^r = 2^2r

 

log 5 + r log 2   = 2r log 2

log 5 = r (2log2 - log2)

 

log5 / log 2 = r   = 2.321928095             (and k = 3/5)

 Aug 7, 2020
 #2
avatar+169 
+1

Isnt this and the other thing you posted,

   https://web2.0calc.com/questions/help_37869

the same question?

 Aug 8, 2020

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