Question

Which ordered pair is a solution of the equation 2x − y = 9?

Answer 1

The correct answer is:    [C]:    " (5, 1) ".

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Explanation:

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Choice:  [C]:  " x = 5 " ;  " y = 1 " ;

Note:  Given the equation:  " 2x - y = 9 " .

  → Plug in " 5 " for "x" , and " 1  for " y " ;

to get:   " [2 * 5]  -  [1]   =   10  -  1  =  " 9 " ;  and:  " 9  =  9 " .

So,  Choice:  [C]:  " (5, 1) "  — is the CORRECT ANSWER.

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Let us consider the "other answer choices" ; as follows:

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Choice:  [A]:  "x = - 4 " , "y = 1" ;  Plug in these values for the given equation:

→  " 2x - y = 9 " ;

→  " (2 * -4) - (5) = - 8 - 5 =  " - 13 "  ;  and:  " - 13 ≠ 9 " .

→  So:  Answer choice:  [A]:  is INCORRECT.

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Choice [B]:  "x = -2" , "y = 5" ;  Plug in these values for the given equation:

  "2x - y = 9 " ;

→  " (2 * -2) - (5) = -4 - 5 = -9 ;  and:  " -9 ≠ 9 " .

→  So:  Answer choice:  [B]:  is INCORRECT.

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Choice:  [D]:  "x = 6 " , "y = - 3" ;  Plug in these values for the given equation:

  "2x - y = 9 " ;

→  " (2 * 6) - ( -3) =  12 - (-3)  =  12 + 3  = " 15 " ;  and:  " 15 ≠ 9 " .

→  So:  Answer choice:  [D]:  is INCORRECT.

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     →  The correct answer is:    [C]:    " (5, 1) " .

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Answer 2

The ordered pairs represents x and y . So you just started plug in the first numbers as “x” and the second as “y”. For example 2(-4)-(1)=9 . This will not get you the solution 9 , it gives you -8 -1 which is -9.

The correct order pair is (5,1). Here’s why

2(5)-(1)=9 is true because:

10-1=9  therefore

The ordered pair is (5,1)