Question

若a减b=3,则a的平方减b的平方减6a等于多少

Answer 1

a-b=3

a的平方减b的平方减6a

=(a+b)(a-b)-6a

=3(a+b)-6a

=3a+3b-6a

=-3a+3b

=-3(a-b)

=-3*3

=-9