Find the value of `x^3-8y^3-36 x y-216 ,` when `x=2y+6.`

Explanation

To find the value of the expression \( x^3 - 8y^3 - 36xy - 216 \) when \( x = 2y + 6 \), we can follow these steps:

### Step 1: Substitute \( x \) in the expression
We start by substituting \( x = 2y + 6 \) into the expression:

\[ (2y + 6)^3 - 8y^3 - 36(2y + 6)y - 216 \]
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