Question

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Answer 1

Answer:

Hi there!

The correct answer is: $2x^{2} + y^{2} + z^{2} - 2\sqrt{2} xy - 2\sqrt{2} xz + 2yz$

Step-by-step explanation:

First of all I want to clarify I used to the fourth identity to solve this problem.

The fourth identity is: $(x+y+z)^{2} = x^{2} + y^{2} + z^{2} + 2xy + 2xz + 2yz$