極限問題?(題目錯了,已更正)(已解答)

看板trans_math作者 (acgrun)時間17年前 (2007/06/12 00:06), 編輯推噓0(003)
留言3則, 1人參與, 最新討論串1/1
*不好意思,題目打錯了,兩題都應該是 ^(1/2) 又有兩題關於極限的問題,我想了半天還是解不出來, 不知是不是因式分解方面的問題,請高手解答一下,謝謝 2-(x+4)^(1/2) 1 1. lim _____________ = - ___ x->0 x 4 2-(x+4)^(1/2) lim _____________ x->0 x [2-(x+4)^(1/2)] [2+(x+4)^(1/2)] = lim __________________________________ x->0 x [2+(x+4)^(1/2)] 2^2 - [(x+4)^(1/2)]^2 = lim _________________________________ x->0 x [2+(x+4)^(1/2)] 4 - (x+4) = lim _________________________________ x->0 x [2+(x+4)^(1/2)] - x = lim _______________________________- x->0 x [2+(x+4)^(1/2)] 1 = - ___ 4 1 1 2. lim ___ ( ___________ - 1 ) x->0 x (1+x)^(1/2) 1 1 lim ___ ( ___________ - 1 ) x->0 x (1+x)^(1/2) 1 1 (1+x)^(1/2) = lim ___ ( ________________ - _____________ ) x->0 x (1+x)^(1/2) (1+x)^(1/2) 1 1 - (1+x)^(1/2) = lim ___ ( ___________________________ ) x->0 x (1+x)^(1/2) 1 [1-(1+x)^(1/2)] [1+(1+x)^(1/2)] = lim ___ ( _______________________________________ ) x->0 x (1+x)^(1/2) [1+(1+x)^(1/2)] 1 1- (1+x) = lim ___ ( ________________________________________ ) x->0 x (1+x)^(1/2) [1+(1+x)^(1/2)] 1 - x = lim ___ ( ________________________________________ ) x->0 x (1+x)^(1/2) [1+(1+x)^(1/2)] - 1 = lim ______________________________ x->0 (1+x)^(1/2) [1+(1+x)^(1/2)] 1 = - ___ 2 -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 218.168.165.104

06/12 00:12, , 1F
第一題題目錯了,應該是根號吧
06/12 00:12, 1F

06/12 00:12, , 2F
然後第一題把分子有理化之後約分就好了
06/12 00:12, 2F

06/12 00:13, , 3F
第二題通分完消掉再約分,答案就出來了
06/12 00:13, 3F
※ 編輯: acgrun 來自: 218.168.156.52 (06/12 04:27) ※ 編輯: acgrun 來自: 218.168.156.52 (06/12 05:29)
文章代碼(AID): #16RNCFWD (trans_math)