The correct response to explain why \( \frac{ad + bc}{bd} \) is a rational number is:
By the Closure Property, \( ad + bc \) and \( bd \) are both integers, and so \( \frac{ad + bc}{bd} \) is a quotient of two integers.
Here's the reasoning:
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Closure Property: This property states that the set of integers is closed under addition and multiplication. This means that when you add or multiply integers, the result is also an integer.
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Since \( a, b, c, \) and \( d \) are integers, we can conclude that:
- The sum \( ad + bc \) is an integer because it involves integer multiplication and addition.
- The product \( bd \) is also an integer since it involves integer multiplication.
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A rational number is defined as a quotient of two integers (where the denominator is not zero). In this case, \( \frac{ad + bc}{bd} \) is a quotient of the integer \( ad + bc \) and the integer \( bd \) (which is non-zero because \( b \) and \( d \) are non-zero).
Therefore, \( \frac{ad + bc}{bd} \) qualifies as a rational number.