Solution:

(a+b+c)？ =0

Answer? +b？ +c？ +2ab+2ac+2bc=0

1+2ab+2ac+2bc=0

2ab+2ac+2bc=- 1

therefore

Primitive formula

=ab+ac+bc+ab+ac+bc

=2ab+2ac+2bc

=- 1

Question 16:

Solution:

x+ 1/x= 13/6

(x+ 1/x)？ =( 13/6)?

x？ + 1/x？ +2= 169/36

x？ + 1/x？ =97/36

therefore

Primitive formula

=x？ + 1/x？ +3(x+ 1/x)- 1

=97/36+3× 13/6- 1

=97/36+ 13/2- 1

=295/36

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