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金钱 柯币
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发表于 2006-10-19 02:50:33
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回复: English Chatroom (想练习英语的就来啊^^)
[quote=棉花糖糖]how do you know it is 2[/quote]
have u learned the sign rule? there are one sign changes if u subs. x into the equation (it tells u there's one positive solution in the answer); if u substitute -x in it, there are 2 sign changes takes place(it tells u there are 2 or 0 (it could be imaginary numbers) negative real #solutions
remember this will increase the chances of guessing correctly and not waste ur time~
[quote=SoloSurViVOR]it should be a factor of 24, usually. My first attemp was x = -2, merely from my instinct. Normally people have to try 3 times to get it right. Here i...[/quote]
err, i dont think it's someones innate abi. to get that... the reason u got it b/c uve learned it and had enough practice = = ||| |
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