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Which shows the correct way to use the rule "multiply by the reciprocal" for the expression below: 5 - 5/9?

A. 5 - (5/9)
B. (5 - 5)/9
C. 5 - (9/5)
D. 5 - (5/9) x 9

1 Answer

3 votes

Final answer:

The correct way to use the rule 'multiply by the reciprocal' for the expression 5 - 5/9 is demonstrated in option D: 5 - (5/9) x 9, which properly applies the multiplication of 5/9 by its reciprocal before subtracting from 5.

Step-by-step explanation:

The question asks which option demonstrates the correct way to apply the rule 'multiply by the reciprocal' for the expression 5 - 5/9. The reciprocal of a number is what you multiply that number by to get 1. In this case, the reciprocal of 5/9 is 9/5. Therefore, to subtract 5/9 from 5 using multiplication by the reciprocal, you would multiply 5/9 by its reciprocal, which is 9/5, and then subtract this result from 5. Let's look at the options presented.

  • A. 5 - (5/9) simply restates the original expression.
  • B. (5 - 5)/9 suggests dividing the result of 5 - 5 by 9, which is not using the reciprocal correctly.
  • C. 5 - (9/5) incorrectly uses the reciprocal of the whole number 5, rather than of 5/9.
  • D. 5 - (5/9) x 9 correctly applies the rule by multiplying 5/9 by 9, which is its reciprocal, and then subtracting the result from 5.

The correct answer is D. 5 - (5/9) x 9, as it correctly uses the 'multiply by the reciprocal' rule by multiplying 5/9 by 9 before subtracting from 5.

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