Question

Which of the following expressions is correct?

Answer 1

Answer:

The correct answer is: [A]: " -(-21)  =  21 " .

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Step-by-step explanation:

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Let us examine the answer choices given.

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Choice:  [A]:  " -(-21) = 21 .  This is correct;  

     → since a "negative value of negative value" is a "positive value" ; as shown in this case.  The equal sign holds true, since the

"negative of a "negative value" is equal to the "positive value" of that same "positive value equivalent."

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Choice: [B]:  " -(-21) = -21 .  This is incorrect.  As explained above:

    → a "negative of negative" is a "positive value"  .

This answer choice shows that a "negative of negative"; is a "negative" :

                                                      → which is:  INCORRECT.

    → Rule out:  "Choice:  [B]."

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Choice: [C]:  " -(21) = 21 .  This is incorrect.  The "negative" value [of a positive integer is not equal to the "equivalent positive value" of that same integer.

   → Rule out:  "Choice:  [C]."

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Choice: [D]:  " (-21) = 21 ";  This is incorrect.  In a conceptually similar way as explained above—(for  "Answer Choice:  [C]" — the "negative value equivalent" of an integer is NOT equal to the "equivalent positive value" [of that same integer.].

  → Rule out:   "Choice:  [D]."

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The correct answer is:  [A]:  " -(-21) = 21 " .

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Hope this is helpful to you!

   Best wishes!

Answer 2

Answer: the correct answer is A

Step-by-step explanation:

Your welcome :)