作业帮 > 英语 > 作业

Fill in each blank with an answer as easy as possible.

来源:学生作业帮 编辑:作业帮 分类:英语作业 时间:2024/10/03 00:59:51
Fill in each blank with an answer as easy as possible.
(a)M is a triangular number if and only if___________ is an odd square number.
(b)N is an odd square number if and only if____________is a triangular number.
triangular number:n(n+1)/2,square number:n^2.
(a)
M = n(n+1)/2
等价于:8M+1 = 4 n^2 + 4 n + 1 = (2n+1)^2
所以,第1个空应该填:8M+1
(b)
N = (2n+1)^2
等价于:(N-1) / 8 = n(n+1)/2
所以,第2个空应该填:(N-1)/8