(A)
設X+1/X = A
以A表示X^2 + 1/X^2
(B)
解方程
6(X^2 + 1/X^2) - 5 (X + 1/X) - 38 = 0
中四數學題 二元二次方程
2010-10-17 9:00 am
回答 (1)
2010-10-17 9:54 am
✔ 最佳答案
a. x + 1/x = A(x + 1/x)^2 = A^2
x^2 + 2 + 1/x^2 = A^2
x^2 + 1/x^2 = A^2 - 2
b. By a,
6(A^2 - 2) - 5A - 38 = 0
6A^2 - 5A - 50 = 0
A = 10/3 or -5/2
x + 1/x = 10/3 or x + 1/x = -5/2
3x^2 - 10x + 3 = 0 or 2x^2 + 5x + 2 = 0
x = 3,1/3 or -1/2,-2
參考: me
收錄日期: 2021-04-13 17:35:35
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20101017000051KK00103