Question

a为9+根号13,b为9-根号13,a+b=2*根号13,求ab-4a+3b-2

Answer 1

a+b=9+√13+9-√13=18

a+b=2√13

条件相互冲突

舍去a+b=2√13

解题如下：

ab=(9-√13)(9+√13)

=81-13

=68

a-b=(9+√13)-(9-√13)

=(9+√13)-9+√13

=2√13

ab-4a+3b-2

=68-3(a-b)-a-2

=68-3*2√13-(9+√13)-2

=68-6√13-9-√13-2

=57-7√13