Question

a^2+b^2+c^2-ab-bc-ca equals to
options are:
a) (a+b+c)^2
b) (a-b-c)^2
c) (a-b+c)^2
d) 1/2{(a-b)^2+(b-c)^2+(c-a)^2}

Answer 1

Answer:

(a+b+c)^2 option c

Step-by-step explanation:

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Answer 2

Answer:

a^2+b^2+c^2-ab-bc-ca

=1/2(2a^2+2b^2+2c^2-2ab-2bc-2ca)

=1/2{(a^2-2ab+b^2)+(b^2-2bc+c^2)+(c^2-2ca+a^2)}

=1/2{(a-b)^2+(b-c)^2+(c-a)^2}

so (d) is the correct answer