Question

已知U={-1,1},集合A={x∈U x^2-ax+1=0},若CUA=U,则实数a的集合范围是

Answer 1

U={-1,1},集合A={x∈U| x^2-ax+1=0},

∵CuA=U

∴A=Φ

当Δ=a^2-4 -2