Question

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

A. (-4,1)
B. (-2,5)
C. (5,1)
D. (6,-3)

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)