F.4 數學 - 二次方程 (高手請進)
回答 (3)
2007-10-30 6:29 am
✔ 最佳答案
If the equation has repeated roots, discriminant = 0Discriminant = (-18)^2 - 4(k)(2k) = 0
324 - 8k^2 = 0
324 = 8k^2
81/2 = k^2
k = 9/√2
2007-10-30 6:54 am
Discriminant = 0
(-18)^2 - 4(k)(2k)= 0
(18)^2 - 8k^2= 0
324= 8k^2
2 (sq. root)2k= + / -18
k=9/ (sq. root) 2 or -9/ (sq. root) 2
希望可以幫到你
(-18)^2 - 4(k)(2k)= 0
(18)^2 - 8k^2= 0
324= 8k^2
2 (sq. root)2k= + / -18
k=9/ (sq. root) 2 or -9/ (sq. root) 2
希望可以幫到你
參考: 自己
2007-10-30 6:31 am
coz有一個二重實根
so delta=0
so (-18)^2-4(k)(2)=0
324-8k=0
-8k=-324
k = 81/2
2007-10-29 22:36:24 補充：
aiya中間打錯野係 so (-18)^2-4(k)(2k)=0 324-8k^2 = 0 -8k^2 = -324 k^2 = 81/2 k= 9/√2 or k= -9/√2 coz要開方所以會正副( /-)so2個answer
so delta=0
so (-18)^2-4(k)(2)=0
324-8k=0
-8k=-324
k = 81/2
2007-10-29 22:36:24 補充：
aiya中間打錯野係 so (-18)^2-4(k)(2k)=0 324-8k^2 = 0 -8k^2 = -324 k^2 = 81/2 k= 9/√2 or k= -9/√2 coz要開方所以會正副( /-)so2個answer
參考: mine ah
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