x1,x2是方程x²+x-3=0的两根,所以x1+x2=-1,x1x2=-3.
因为x²+x-3=0,所以x³+x²-3x=0,x³=-x²+3x
x1³-x2²+30=-x1²+3x1-x2²+30
=(x1-x2)(x1+x2)+3x1+30
=-(x1-x2)+3x1+30
=2x1+x2+30
=x1+29....ʮ�ֲ�����˼,��Ŀ�����,�鷳�ٽ�һ��...��X1,X2Ϊ����x²+X-3=0��������,��X1³-4X2²+30��ֵx1，x2是方程x²+x-3=0的两根，所以x1+x2=-1，x1x2=-3.因为x²+x-3=0，所以x³+x²-3x=0，x³=-x²+3xx1³-4x2²+30=-x1²+3x1-4x2²+30=-x1²-x1+4x1-4x2²+30=4x1-4x2²+27=4x1-4(-x2+3)+27=4(x1+x2)+15=11.