Math : Find the root

2014-01-10 7:08 pm
Solve X^4 - 2X^2 - 1 = 0, giving the roots correct to 2 dec.

回答 (4)

2014-01-10 7:58 pm
✔ 最佳答案
X⁴ - 2X² - 1 = 0
X²=[2±√((-2)²-4(1)(-1))] / (2)
X²=(2±√8)/2
X²=(2±2√2)/2
X²=1±√2
X=±√(1±√2)

2014-01-10 11:59:56 補充:
X=
√(1+√2)
or
-√(1+√2)
or
√(1-√2)
or
-√(1-√2)

2014-01-10 12:02:52 補充:
X=
1.55
or
-1.55
or
0.64 i
or
-0.64 i

i=√(-1)
2014-01-11 12:39 am
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2014-01-10 9:51 pm
哦~~

你在中午出現!??!!?

2014-01-10 14:52:09 補充:
嘻~~

你真的很可愛~ (。◕‿◕。)
2014-01-10 8:02 pm
x⁴- 2x² - 1 = 0
(x⁴- 2x² + 1) - 2 = 0
(x² - 1)² - 2 = 0
(x² - 1)² = 2
x² - 1 = ±√2
x² = 1 ± √2
x = ± √(1 ± √2)
x = √(1 + √2) or - √(1 + √2) or √(1 - √2) (rejected) or - √(1 - √2) (rejected)
x = 1.55 or - 1.55

2014-01-10 14:20:30 補充:
噢 ~ ~

我昨晚洗了件隱身衣,到中午都未乾。


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