Question

【 20 分】1.已知 a+b=3,ab=-12,求下列个值【1】a^2+b^2 [2][a-b]^22.2005^2-

Answer 1

1.a+b=3

(a+b)^2=9

a^2+b^2+2ab=9

a^2+b^2 =9+24=33

a^2+b^2=33

-2ab=24

a^2+b^2-2ab=57

[a-b]^2=57

2.2005^2-(2005+1)*(2005-1)

=2005^2-2005^2+1^2

=1