Question

If a + b +c = 0 and a2 + b2 + c2 = 20, find ab + bc + ca.

Answer 1

Answer:

( a+ b + c) 2 = a2 + b2 + c2 + 2 ( ab + bc + ac)

ab + bc + ac = --20 / 2 = -10

Step-by-step explanation:

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Answer 2

Answer:

-10.

Step-by-step explanation:

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