第一题1+x+x^2=0x^1980+x^1981+……+x^2000=x^1980(1+x+x^2+……+x^20)=x^1980[(1+x+x^2)+x^3(1+x+x^2)+x^6(1+x+x^2)+……+x^18(1+x+x^2)]=0第二题x^2+6x+9=0(x+3)^2=0x=-3x^2-121=0(x-11)(x+11)=0x1=11或x2=-11(x-2...