已知,a-b=5,ab=3则(a+1)(b-1)的值为?A:-1B:-3C:1D:3

来源:学生作业帮助网 编辑:六六作业网 时间:2024/11/28 01:13:46
已知,a-b=5,ab=3则(a+1)(b-1)的值为?A:-1B:-3C:1D:3已知,a-b=5,ab=3则(a+1)(b-1)的值为?A:-1B:-3C:1D:3已知,a-b=5,ab=3则(a

已知,a-b=5,ab=3则(a+1)(b-1)的值为?A:-1B:-3C:1D:3
已知,a-b=5,ab=3则(a+1)(b-1)的值为?A:-1B:-3C:1D:3

已知,a-b=5,ab=3则(a+1)(b-1)的值为?A:-1B:-3C:1D:3
把(a+1)(b-1)拆开,
得到ab-a+b-1=ab-(a-b)-1
把数代入得到3-5-1=-3
选B

(a+1)(b-1)
=ab+b-a-1
=3-5-1
=-3
选择B