若以下各二次方程沒有實根,求k值的範圍。
(k+1)X* =4X-1----------(X*代表X二次方)
中4數學題~(急)
2006-10-15 6:44 am
回答 (4)
2006-10-15 6:47 am
✔ 最佳答案
(k+1)X^2 =4X-1(k+1)X^2 -4X +1 =0
△ = (-4)^2 - 4(k+1) = 16 - 4k -4 = 12 - 4k
∵二次方程沒有實根
∴△ ＜0
12 - 4k＜0
-4k＜-12
k＞3
2006-10-15 6:23 pm
(k+1)X^2 =4X-1
(k+1)X^2 -4X +1 =0
△ = (-4)^2 - 4(k+1) = 16 - 4k -4 = 12 - 4k
∵二次方程沒有實根
∴△ ＜0
12 - 4k＜0
-4k＜-12
k＞3
(k+1)X^2 -4X +1 =0
△ = (-4)^2 - 4(k+1) = 16 - 4k -4 = 12 - 4k
∵二次方程沒有實根
∴△ ＜0
12 - 4k＜0
-4k＜-12
k＞3
2006-10-15 6:57 am
(k+1)X* =4X-1
(k+1)x* - 4x + 1 = 0
∵The equation (k+1)X* =4X-1 has no roots
∴ △ < 0
(-4)* - 4(k+1) < 0
16 - 4k - 4 < 0
-4k < 12
k > -3
2006-10-14 22:58:26 補充：
< = ＜> = ＞
(k+1)x* - 4x + 1 = 0
∵The equation (k+1)X* =4X-1 has no roots
∴ △ < 0
(-4)* - 4(k+1) < 0
16 - 4k - 4 < 0
-4k < 12
k > -3
2006-10-14 22:58:26 補充：
< = ＜> = ＞
2006-10-15 6:52 am
(k+1)X* =4X-1
(k+1)X* -4X+1=0
no real root
b*-4(a)(C)<0
16-4(k+1)(1)<0
15-4k<0
k>15/4
2006-10-14 22:55:39 補充：
b*-4(a)(C) < 016-4(k 1)(1) < 015-4k < 0k > 15/4
2006-10-14 22:56:58 補充：
＞＜b*-4(a)(C) ＜ 016-4(k 1)(1) ＜ 015-4k ＜ 0k ＞15/4
2006-10-14 23:01:04 補充：
sorry I wrongb*-4(a)(C) ＜ 016-4(k 1)(1) ＜ 015-4k-4＜ 0k ＞ 3it is right
(k+1)X* -4X+1=0
no real root
b*-4(a)(C)<0
16-4(k+1)(1)<0
15-4k<0
k>15/4
2006-10-14 22:55:39 補充：
b*-4(a)(C) < 016-4(k 1)(1) < 015-4k < 0k > 15/4
2006-10-14 22:56:58 補充：
＞＜b*-4(a)(C) ＜ 016-4(k 1)(1) ＜ 015-4k ＜ 0k ＞15/4
2006-10-14 23:01:04 補充：
sorry I wrongb*-4(a)(C) ＜ 016-4(k 1)(1) ＜ 015-4k-4＜ 0k ＞ 3it is right
收錄日期: 2021-04-13 13:42:23
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20061014000051KK06361