To determine why \( \frac{ad + bc}{bd} \) is a rational number given that \( a, b, c, \) and \( d \) are integers and \( b \) and \( d \) are non-zero, we need to look at the definitions and properties of rational numbers.
A rational number is defined as a number that can be expressed as the quotient (or fraction) of two integers, where the denominator is not zero.
Let's analyze the responses based on this understanding:
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By the Closure Property, \( ad + bc \) and \( bd \) are both quotients of integers, and so \( \frac{ad + bc}{bd} \) is a quotient of two integers.
- This is incorrect because \( ad + bc \) and \( bd \) are not quotients of integers; rather, they are the results of integer operations.
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By the Closure Property, \( ad + bc \) and \( bd \) are both quotients of integers, and so the fraction with numerator \( ad + bc \) and denominator \( bd \) is a quotient of two integers.
- This is similar to the first option and is also incorrect for the same reasoning.
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By the Closure Property, \( ad + bc \) and \( bd \) reduce to a whole number, which is a subset of rational numbers.
- This statement is misleading since it asserts a reduction to whole numbers without proper justification and doesn't clarify the structure of \( ad + bc \) and \( bd \) as integers.
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By the Closure Property, the fraction with numerator \( ad + bc \) and denominator \( bd \) reduces to a whole number, which is a subset of rational numbers.
- Like the previous option, this one is misleading and does not effectively prove the statement.
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By the Closure Property, a quotient of imaginary numbers is a rational number.
- This is incorrect as it deals with imaginary numbers, which are not relevant in this case since we are dealing with integers.
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By the Closure Property, \( ad + bc \) and \( bd \) are both integers, and so \( \frac{ad + bc}{bd} \) is a quotient of two integers.
- This is the correct response. Since both \( ad + bc \) and \( bd \) are integers (with \( bd \) being non-zero), the fraction \( \frac{ad + bc}{bd} \) is indeed a valid quotient of two integers, thus forming a rational number.
Given this analysis, the correct explanation is:
By the Closure Property, \( ad + bc \) and \( bd \) are both integers, and so \( \frac{ad + bc}{bd} \) is a quotient of two integers.