To find the length of the remaining piece of the wooden beam after cutting off a certain piece, we need to perform a polynomial subtraction.
The initial length of the wooden beam is given by:
\[ 6y^2 + 7y + 1 \]
The length of the piece cut off is:
\[ y^2 - 9 \]
To find the remaining length, we subtract the length of the piece cut off from the original length:
\[ (6y^2 + 7y + 1) - (y^2 - 9) \]
Let's perform the subtraction step-by-step.
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Distribute the negative sign in front of the second polynomial: \[ 6y^2 + 7y + 1 - y^2 + 9 \]
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Combine like terms:
- For the \(y^2\) terms: \(6y^2 - y^2 = 5y^2\)
- For the \(y\) terms: \(7y\) (there is no corresponding \(y\) term in the second polynomial)
- For the constant terms: \(1 + 9 = 10\)
Putting it all together, we have:
\[ 5y^2 + 7y + 10 \]
Thus, the length of the remaining piece of the beam is:
\[ \boxed{5y^2 + 7y + 10} \]