Formula:
-b±√b²-4(a)(c)
-------------------
2(a)
.............................
1) 3x²-2x+2=0
請問以下步驟正確嗎?
2 ±√4-4(3)(2)/ 2(3)
那麼答案應該是..?
..........................
2) x(x-2)+(x-3)(x-4) =122
應該怎樣做呢?
3) (2x-1)(5x+2)(2x-1)²=0
應該怎樣做呢?
謝謝!
F4 Quadratic Equations in one unknown
2008-09-17 6:38 am
回答 (1)
2008-09-17 6:55 am
✔ 最佳答案
1) 對~ 但因為4-4(3)(2)<0, 所以無實根.複數根
={2 ±√[4-4(3)(2)]}/ 2(3)
= 1/3(1±i√5) , i = √-1
2) x(x-2)+(x-3)(x-4) =122
x^2-2x+x^2-7x+12=122
2x^2-9x-110=0
x = {9 ±√[81-4(2)(-110)]}/ 2(2)
= 10 or -5.5
3) (2x-1)(5x+2)(2x-1)^2=0
(5x+2)(2x-1)^3=0
5x+2=0 or 2x-1=0
x=-2/5 or 1/2
收錄日期: 2021-04-13 16:06:10
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20080916000051KK02472