3

If x = 12, then plugging "12" in for "x" in the original equation should work. Let's see:

. . . . .3([12] - 5) ?=? [12] + 9

. . . . .3(7) ?=? 21

. . . . .21 ?=? 21

This certainly looks like a valid solution to me. Checking over your work, all your steps look perfectly correct.

I have no idea what your instructor might be getting at, but, if the problem is as posted, you're right.

Eliz.
 
The equation you posted is:
3(x-5) = (x+9)
and x = 12 is correct as Eliz told you.

Are you sure you're using same equation as your teacher?
The right side make me suspicious: why the brackets?
Looks like that could be 2(x+9)...or something(x+9).
 
Dark Knight 496 said:
Some teachers just won't admit their mistakes.
Sad, but true.

Me, I gave up trying to look "perfect" a long time ago, partly because I mess up so regularly that nobody would have bought it, but mostly because the students really pay attention to the material if they know they can get extra-credit points for finding my mistakes. :wink:

Eliz.
 
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