Find the coefficient of : `x^(-15)` in the expansion of `(3x^2-a/(3x^3))^(10)dot`

Explanation

To find the coefficient of \( x^{-15} \) in the expansion of \( \left( 3x^2 - \frac{a}{3x^3} \right)^{10} \), we will follow these steps:

### Step 1: Write the General Term
The general term \( T_{r+1} \) in the binomial expansion is given by:
\[ T_{r+1} = \binom{10}{r} (3x^2)^{10-r} \left(-\frac{a}{3x^3}\right)^r \]

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