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January 31, 2015

January 31, 2015

Posted by **anon** on Sunday, December 18, 2011 at 6:03pm.

log_2 (x -1)- log_2(5x +1) = -3

I got -3, is this correct???????

- algebra -
**Steve**, Sunday, December 18, 2011 at 7:13pmassuming base 2 for ease of reading,

log(x-1) - log(5x+1) = -3

log[(x-1)/(5x+1)] = -3

(x-1)/(5x+1) = 2^-3 = 1/8

8(x-1) = 5x+1

8x - 8 = 5x + 1

3x = 9

x = 3

log 2 - log 16 = 1 - 4 = -3

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