Question

请帮忙解答 谢谢

已知全集u={x┃2≤x≤30},集合A={x┃x=2n,n∈N*} 集合B=｛x┃x=3n+1，n∈N*｝ C=｛x┃x是素数｝，求Cu（A∪B）∩C 请帮忙 谢谢

Answer 1

U={x|2≤x≤30}
A={x|x=2n,n∈N*}={2,4,6,8,10,12,14,16,18,20,22,24,26,28,30}
B={x|x=3n+1,n∈N*}={4,7,10,13,16,19,22,25,28}
C={x|x是素数}={2,3,5,7,11,13,17,19,23,29}

所以A∪B={2,4,6,7,8,10,12,13,14,16,18,19,20,22,24,25,26,28,30}
故Cu(A∪B)={3,5,9,11,15,17,21,23,27,29}
所以Cu(A∪B)∩C={3,5,11,17,23,29}

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