x^2-6+x+1≤0x^2+x-5≤0x^2+x+1/4-21/4≤0(x+1/2)^2-21/4≤o(x+1/2+√21/2)(x+1/2-√21/2)≤0-1/2-√21/2≤x≤-1/2+√21/2