(x-1)(x-5)=(k-1)(k-5)，則x=?或?
回答 (2)
2007-01-01 3:08 am
✔ 最佳答案
(x-1)(x-5) = (k-1)(k-5) x2 - 6x + 5 = k2 - 6k + 5
x2 -6x - k2 + 6k = 0
x2 - k2 -6x + 6k = 0
(x+k) (x-k)-6(x-k)= 0
(x- k) [(x+k) -6] = 0
(x- k) (x+k -6) = 0
x- k= 0 or x+k-6 = 0
∴x = k or x = 6-k
參考: mE
2007-01-01 6:23 am
我諗呢條係quadratic equation
首先,左右乘哂入去
=x^2-6x-(k^2+6k)=0-------------(1)
跟住搵discriminants
because it has two roots
=6^2-4(-k+6k)>=0
k>=3
代k=3入(1)
x=3or3
PS:6^2=6的2次方,如此類推
首先,左右乘哂入去
=x^2-6x-(k^2+6k)=0-------------(1)
跟住搵discriminants
because it has two roots
=6^2-4(-k+6k)>=0
k>=3
代k=3入(1)
x=3or3
PS:6^2=6的2次方,如此類推
參考: myself
收錄日期: 2021-04-29 16:00:25
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20061231000051KK03448