Question

已知集合A={x|-1≤x≤3},B={y|x²=y,x∈A},C={y|y=2x+a,x∈A},

Answer 1

B={y|y=x^2}因为-1≤x≤3,0≤x^2≤9,B={y|0≤y≤9}

C={y|-2+a≤y≤6+a}

∵C包含于B

∴0≤-2+a

-2+a≤6+a

6+a≤9

即有2≤a≤3