Simplify: `(a+b+c)^2+\ (a-b+c)^2+\ (a+b-c)^2`

Explanation

To simplify the expression \((a+b+c)^2 + (a-b+c)^2 + (a+b-c)^2\), we will use the algebraic identity for the square of a sum, which is given by:

\[ (x+y+z)^2 = x^2 + y^2 + z^2 + 2xy + 2yz + 2zx \]

### Step-by-Step Solution:

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