To find the product of \( (4y + 5)(4y - 4) \), we can use the distributive property (also known as FOIL for binomials).
Here’s how it works step by step:
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First: Multiply the first terms: \[ 4y \cdot 4y = 16y^2 \]
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Outer: Multiply the outer terms: \[ 4y \cdot (-4) = -16y \]
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Inner: Multiply the inner terms: \[ 5 \cdot 4y = 20y \]
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Last: Multiply the last terms: \[ 5 \cdot (-4) = -20 \]
Now, we combine all these products together: \[ 16y^2 - 16y + 20y - 20 \]
Now combine the like terms \(-16y + 20y\): \[ 16y^2 + 4y - 20 \]
Thus, the product of \( (4y + 5)(4y - 4) \) in standard form is: \[ \boxed{16y^2 + 4y - 20} \]