我要問點計個ｘ
Ｘ^2－Ｘ－１＝０
我老師話有方法整走個Ｘ
求高手教路！！
中四簡單數學題！！
2007-09-13 1:58 am
回答 (2)
2007-09-13 2:08 am
✔ 最佳答案
Ｘ^2－Ｘ－１＝０x^2-x+1/4-5/4=0
(x-1/2)^2=5/4
x-1/2= +/- (√5)/2
x=1/2 +/- (√5)/2
x=[1 +/- (√5)]/2
∴x=[1+(√5)]/2 or x=[1-(√5)]/2
{x=1.62 or x=-0.62 (2 decimal places)}
參考: me
2007-09-13 2:22 am
in general to solving this kind of quadratic equation Ax^2 + Bx +C = 0
the general solution is
x = {-B +/- [sqrt (B^2 - 4AC)] } / 2A
the general solution is
x = {-B +/- [sqrt (B^2 - 4AC)] } / 2A
收錄日期: 2021-04-21 13:57:53
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070912000051KK02393