Question

由集合{a1}，{a1，a2}，{a1，a2，a3}，…的子集个数归纳出集合{a1，

a2，a3，…，an}的子集个数为( )

A．n B．n＋1

C．2n D．2n－1

 

Answer 1

C

【解析】集合{a1}的子集有∅，{a1}共2个；{a1，a2}的子集有∅，{a1}，{a2}，{a1，a2}共4个；集合{a1，a2，a3}的子集共8个，猜测n个元素的集合的子集有2n个，故选C.