设x1、x2是方程x平方+5x-7=0的两个实数根,则(x1-1)(x2-2)的值为

求根公式
x1 = (-5 + 根号(53))/2
x2 = (-5-根号(53))/2
那么
x1 + x2 = -5
x1 * x2 = -28/4 = -7
那么
(x1-1)(x2-1)= x1x2 -x1-x2+1 = -5 - (-7) + 1 = 3嘻嘻，对不起，选项中没有这个答案代入错了x1 + x2 = -5x1 * x2 = -28/4 = -7那么(x1-1)(x2-1)= x1x2 -x1-x2+1 = -7 - (-5) + 1 = -1这次有了，谢谢咯，下次还找你帮忙！下次还问啊...要学会自己算...