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[MikeRWolf]

Hello everyone, first time poster here. Here is the problem that is driving me insane. My teacher gives us a review packet with problems and another packet with the solutions to them. Can somebody please tell me where the +12x +12x came from?! Seems like out of thin air to me!

Much appreciated.

 

[MikeRWolf]

apologies about the small picture, give me a minute.

 

[MikeRWolf]

 

[MikeRWolf]

Thank you for your reply, much help!

 

[lookagain]

Thank you for your reply, much help!

MikeRWolf, the work shown in the last two lines of the "box" is incorrect. You have this equation:

\(\displaystyle 0 \ = \ 9x^2 + 20x - 4\)


It has to be this one instead:


\(\displaystyle 0 \ = \ 9x^2 + 20x + 4\)


And that will change your last line, not to mention it will start out with "x =," not "0 =."

Also, you must check each of your solutions by substituting them in the original equation
to see if you have to discard any of them (if they don't check).