問:: 求 (X既2次) - 2X - 3 > 0 的解集
答::
(X既2次) - 2X - 3 > 0
(X-3)(X+1)> 0
X< -1 或 X> 3
所以 (X既2次) - 2X - 3 > 0 的解集是 X< -1 或 X> 3
我想問點解(X+1)>0 中的 > 會改變佐.....變成X<-1 ?????
這條式的解集為何是 X< -1 或 X> 3 ???
晤該幫下我解答.....THX!!!
數學一元一次的解集的問題.....
2008-10-19 9:25 pm
回答 (1)
2008-10-23 9:39 pm
✔ 最佳答案
(x-3)(x+1)>0So, there will be two cases :
(i) (x-3)>0 & (x+1)>0,
OR
(ii) (x-3)<0 and (x+1)<0
For case (i), to make sure this happens, x must be >3
For case (ii), to make sure this happens, x must be <1
So, the answer for the question should be (x>3) or (x<1)
收錄日期: 2021-04-13 16:10:26
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20081019000051KK01020