Question

(a+b)+C=a+(b+C) for a= -1, b=2,C=5
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Answer 1

Answer:

a+b+c=5 a

2

+b

2

+c

2

=29

(a+b+c)

2

=a

2

+b

2

+c

2

+2ab+2bc+2ca

25=29+2(ab+ac+bc)

2(ab+bc+ac)=−4

ab+bc+ac=−2