如題,
還有
-7既負2次方=1/-7^2次方
是不是=1/49
如果是,為什麼是正數而不是-1/49???
負7既負2次方為什麼變分數???
2010-09-12 6:59 am
回答 (4)
2010-09-12 2:53 pm
✔ 最佳答案
首先define咗咩叫0次方先：x^0
=x^1/x^1
=x/x
=1
跟住define咩叫負1次方：
x^-1
=x^0/x^1
=1/x
再define咩叫負y次方：
x^-y
=(x^-1)^y
=(1/x)^y
=1^y/x^y
=1/x^y
之後先計(-7)^-2
根據x^-y=1/x^y，x=-7，y=2
(-7)^-2
=1/(-7)^2
=1/(-7)(-7)
負負得正：
=1/49
(負數既雙數次方係正數，單數次方係負數)
參考: 我
2010-09-12 7:14 am
咁-7有無()先
如果有,就=1/49
如果無=-1/49
*小心()呀!~!
如果有,就=1/49
如果無=-1/49
*小心()呀!~!
2010-09-12 7:13 am
(-7)^-2
=[1/(-7)]^2
=(1^2)/(7^2)
=1/49
=[1/(-7)]^2
=(1^2)/(7^2)
=1/49
2010-09-12 7:06 am
-7*-7=49
7*-7=-49
since that that -7 to the power -2 is (-7)^-2,
it equals to 1/49 but not 1/-49.
7*-7=-49
since that that -7 to the power -2 is (-7)^-2,
it equals to 1/49 but not 1/-49.
收錄日期: 2021-04-23 23:21:26
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20100911000051KK01879