设全集U=R.M={m|方程mx^2-x-1=0有实数根},N=|n|方程x^2-x+n=0有实数根},球(CuM)nN

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设全集U=R.M={m|方程mx^2-x-1=0有实数根},N=|n|方程x^2-x+n=0有实数根},球(CuM)nN设全集U=R.M={m|方程mx^2-x-1=0有实数根},N=|n|方程x^2

设全集U=R.M={m|方程mx^2-x-1=0有实数根},N=|n|方程x^2-x+n=0有实数根},球(CuM)nN
设全集U=R.M={m|方程mx^2-x-1=0有实数根},N=|n|方程x^2-x+n=0有实数根},球(CuM)nN

设全集U=R.M={m|方程mx^2-x-1=0有实数根},N=|n|方程x^2-x+n=0有实数根},球(CuM)nN
M={m|方程mx^2-x-1=0有实数根}
①当m=0时,方程有解.∴m=0符合题意
②当m≠0时,Δ=1+4m≥0→m≥-1/4
∴M={m|m≥-1/4}
∴CuM={m|m<-1/4}
N={n|方程x^2-x+n=0有实数根}
Δ=1-4n≥0→n≤1/4
∴N={n|n≤1/4}
∴(CuM)nN={m|m<-1/4}