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最佳答案:2X平方-4X-1=0x1+x2=2x1x2=-1/2x1^2+x2^2=(x1+x2)^2-2x1x2=3(x1x2)^2=1/4所以新方程为x^2-3x+1
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最佳答案:x^2+mx+n=0x1+2x1=-m,x1*2x1=nx1=-m/3,(x1)^2=n/2(m/3)^2=n/2m^2=9n/2△=m^2-4n=1m^2=4