Jonvi
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(2000x)^2-2001×1999x-1=0 ==>(2000x)^2-(2000+1)(2000-1)X-1=0==>
==>(2000x)^2-(2000)^2X+X-1=0==>(2000)^2*X(X-1)+(X-1)=0
==> (2000)^2*X-1)(X-1)=0 ==>其较大根A=1
x^2+1998x-1999=0==>(X-1)(X+1999)=0 其较小根B=-1999
所以A-B=1+1999=2000
1年前
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