Question

若a+b=-3,ab=2,求a2+b2,﹙a-b﹚2,(a-4)(a-4),a4+a4

Answer 1

^是次方的意思

a^2+b^2

=(a+b)^2-2ab

=9-4

=5

﹙a-b﹚^2

=(a+b)^2-4ab

=9-8

=1

(a-4)(b-4)

=ab-4(a+b)+16

=2+12+16

=30

a^4+b^4

=(a^2+b^2)^2-2a^2b^2

=[(a+b)^2-2ab]^2-2a^2b^2

=[9-4]^2-8

=17