当x等于（1或-3 ）时,代数式7x²-5x-1与3x-8x²+4互为相反数7x²-5x-1与3x-8x²+4互为相反数所以7x²-5x-1+3x-8x²+4=0-x²-2x+3=0(x-1)(x+3)=0x=1或-3土豆团邵文潮为您答疑解难.如果本...