x²-3x-1=0则：x²=3x+1原式=2x²*x-3x²-11x+8=2(3x+1)x-3x²-11x+8 把x²=3x+1代入=6x²+2x-3x²-11x+8=3x²-9x+8 再次把x²=3x+1代入=3(3x+1)-9x+8=9x+3-9x+8=11ps：方...