Posted by **Sabrina** on Wednesday, January 5, 2011 at 9:52pm.

Are you allowed to do this

2log(x-1) =log(x+1)

2 (x-1)=(x+1)

x=3

Please help :)

- Math -
**MathMate**, Wednesday, January 5, 2011 at 10:00pm
See:

http://www.jiskha.com/display.cgi?id=1294279972

- Math -
**Reiny**, Wednesday, January 5, 2011 at 11:02pm
Some mathteacher published a book some time ago listing all the silly solutions that students had produced.

It actually had it this way

2log(x-1) =log(x+1)

(2log(x-1))**/log** = (log(x+1))**/log** , then the log/log canceled

2(x-1) = (x+1)

2x - 2 = x+1

x = 3, which by sheer coincidence is the right answer.

- Math -
**MathMate**, Thursday, January 6, 2011 at 7:22am
My teacher showed us this one:

64/16

= (6)4/1(6) [cancel the 6]

= 4/1

= 4

gets the right answer, but the wrong way.

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