Question

用列举法表示下列集合A={x丨x^2=9} B={x∈N丨1≤x≤2} C={x丨x^2-3x+2=0}

Answer 1

A={x丨x^2=9} ={3,-3}

B={x∈N丨1≤x≤2} ={1,2}

C={x丨x^2-3x+2=0}={1,2}