Question

已知集合A{y|y=x2+4,x属于R},B={y|y=1/x,x不等于0},则A交B等于?

Answer 1

A={(x,y)|x^2+mx+2=y},B={(x,y)|x-y+1=0,0≤x≤2},A∩B≠φ

x^2+mx+2=y

x-y+1=0,0≤x≤2

x^2+mx+2=x+1,0≤x≤2

x^2+(m-1)x+1=0,0≤x≤2

△=(m-1)^2-4≥0

m≥3或m≤-1;

又