实周期序列x[n]的基波周期N = 7, x[n]的非零傅里叶级数系数为http://img2.ph.126.net/XcZEVEz5-dK3MzOLu2c83Q==/6608215516029338084.png，http://edu-image.nosdn.127.net/419AFA2F5A1531187DCB45EF46060A23.jpg?imageView&thumbnail=890x0&quality=100。若将x[n]表示成http://edu-image.nosdn.127.net/A2A03272ED5328E9D31CEA139AB794F3.jpg?imageView&thumbnail=890x0&quality=100，则表达式为（ ）。
举一反三
- 中国大学MOOC: 实腹式轴压杆绕x，y轴的长细比分别为http://edu-image.nosdn.127.net/CEDDCE7A3BB52B52DC56A37DE9DF8675.png?imageView&thumbnail=890x0&quality=100，http://edu-image.nosdn.127.net/2715192C2D5C066B84F9EEC130D1DD78.png?imageView&thumbnail=890x0&quality=100，对应的稳定系数分别为http://edu-image.nosdn.127.net/051E7EF77A20CC8EE7AE73090D7D0B9F.png?imageView&thumbnail=890x0&quality=100，http://edu-image.nosdn.127.net/CDC96ACA4577E26B3DE9DBF3AFBCEC46.png?imageView&thumbnail=890x0&quality=100，若http://edu-image.nosdn.127.net/991E5D4B35F3193105567CAF1B1CB1EC.png?imageView&thumbnail=890x0&quality=100，则( ) 。
- 中国大学MOOC: http://edu-image.nosdn.127.net/581311BC4F5E866B4534FB8A2CB01F10.png?imageView&thumbnail=890x0&quality=100如果矩阵X满足AXB＝C，则X是（ ）
- 在图中，图1和图2说明了什么？ http://edu-image.nosdn.127.net/5A4058D817B3257941FD9433C06B41C7.png?imageView&thumbnail=890x0&quality=100 http://edu-image.nosdn.127.net/AA8603CD09CD01384BE2BE87AC9B8F56.png?imageView&thumbnail=890x0&quality=100
- 已知图示有压混联输水管路（按长管计）各管段的沿程阻力系数http://edu-image.nosdn.127.net/1443EEDD6C2FA09BB126BDB9642044BA.png?imageView&thumbnail=890x0&quality=100，管径http://edu-image.nosdn.127.net/974CD2163F1D3BFAAEDC8DA84872F1CA.png?imageView&thumbnail=890x0&quality=100，管长http://edu-image.nosdn.127.net/76A594A1299928A8955B35FC20252D31.png?imageView&thumbnail=890x0&quality=100，流量http://edu-image.nosdn.127.net/1D52DAEDDD85EC829BD9C6E6F96AE143.png?imageView&thumbnail=890x0&quality=100,,则http://edu-image.nosdn.127.net/DAC36D2F41C6C3F84F776BC849094BA1.png?imageView&thumbnail=890x0&quality=100中k=（ ）。http://edu-image.nosdn.127.net/06283F2B8E549ACD83D8DDBBD7E4BE7C.png?imageView&thumbnail=890x0&quality=100
- 中国大学MOOC: 下图中，若http://edu-image.nosdn.127.net/3CC508F9AB3640FC7B4FC8A56BCC3C4A.png?imageView&thumbnail=890x0&quality=100，http://edu-image.nosdn.127.net/1E98E4093ED9A9CF99D5410CB4F9E5FC.png?imageView&thumbnail=890x0&quality=1000011，求http://edu-image.nosdn.127.net/C431073D6B6C788B674E11D5E7EA9B8F.png?imageView&thumbnail=890x0&quality=100（ ）。http://edu-image.nosdn.127.net/3F2606B33B97941F5DFADC9F32BD58AD.png?imageView&thumbnail=890x0&quality=100