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Solve the system of equations \begin{align*} y &= \log_2 (2x), <br /> y &= \log_4 x. \end{align*}Write your answers as ordered pairs  (x,y). If you find more than one solution, list the solutions in order of increasing value of  x and separate your answers with semi-colons. So, for example, you would type "(2,2);(4,6)" to say that  x=2,y=2 and  x=4,y=6 are the two solutions.

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 Dec 14, 2014

Best Answer 

 #1
avatar+23254 
+13

Since  y  =  log2(2x)  --->   2y  =  2x.

Since  y  =  log4(x)   --->   4y  =  x        

           Since  4 = 22,  (22)y  =  x     --->   22y  =  x    

           Since  22y  =  x   --->  2·22y  =  2·x   --->  22y+1  =  2x  =  2y  (from the first equation.

Because  22y+1  =  2y   --->   2y + 1  =  y     --->    y + 1  =  0     --->     y = -1

Becaue   y = -1  and  4y  =  x   --->  x  =  4-1   --->   x  =  1/4 

 Dec 15, 2014
 #1
avatar+23254 
+13
Best Answer

Since  y  =  log2(2x)  --->   2y  =  2x.

Since  y  =  log4(x)   --->   4y  =  x        

           Since  4 = 22,  (22)y  =  x     --->   22y  =  x    

           Since  22y  =  x   --->  2·22y  =  2·x   --->  22y+1  =  2x  =  2y  (from the first equation.

Because  22y+1  =  2y   --->   2y + 1  =  y     --->    y + 1  =  0     --->     y = -1

Becaue   y = -1  and  4y  =  x   --->  x  =  4-1   --->   x  =  1/4 

geno3141 Dec 15, 2014
 #2
avatar+118703 
+1

Thanks Geno,

What ever happened to please anon ??    Maybe it is under the bed.  Maybe you should look :)

 Dec 15, 2014

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