To find the product of \((-8y)\) and \((-7y^4)\), we can follow these steps:
- Multiply the coefficients: \(-8\) and \(-7\).
- Multiply the variable parts: \(y\) and \(y^4\).
Let's calculate it step by step:
-
Multiply the coefficients: \[ -8 \times -7 = 56 \]
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Multiply the variable parts: \[ y \times y^4 = y^{1+4} = y^5 \]
Now combine the results: \[ (-8y) \times (-7y^4) = 56y^5 \]
Thus, the simplified product is: \[ \boxed{56y^5} \]