Find the coefficient of ` a^(3) b^(4)c^(5) ` in the
expasion of `(bc + ca + ab)^(6)`

Explanation

To find the coefficient of \( a^3 b^4 c^5 \) in the expansion of \( (bc + ca + ab)^6 \), we can follow these steps:

### Step 1: Rewrite the expression
We start with the expression \( (bc + ca + ab)^6 \). We need to identify how we can form \( a^3 b^4 c^5 \) from the terms \( bc \), \( ca \), and \( ab \).

### Step 2: Identify contributions from each term
To form \( a^3 b^4 c^5 \), we can express it in terms of the contributions from each of the three terms:
- The term \( ab \) contributes \( a^1 b^1 \).
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