解：4-20i的共轭复数是4+20i(1)x²+x-2=4x²+x-6=0(x+3)(x-2)=0x=-3或x=2(2)x²-3x+2=20x²-3x-18=0(x-6)(x+3)=0x=-6或x=-3所以x=-3
