Versions of Linear Equations Quick Check

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Question
If a line can be represented by the equation y+2=1/3(x−12)
, which of the following sets of points lies on the line?(1 point)
Responses

(−12,2)
and (−9,3)
left parenthesis negative 12 comma 2 right parenthesis and left parenthesis negative 9 comma 3 right parenthesis

(12,−2)
and (13,1)
left parenthesis 12 comma negative 2 right parenthesis and left parenthesis 13 comma 1 right parenthesis

(12,−2)
and (15,−1)
left parenthesis 12 comma negative 2 right parenthesis and left parenthesis 15 comma negative 1 right parenthesis

(−12,2)
and (−11,3)

1 answer

To determine which set of points lies on the line represented by the equation \( y + 2 = \frac{1}{3}(x - 12) \), we first need to convert this equation into a more standard slope-intercept form, \( y = mx + b \).

  1. Start with the given equation: \[ y + 2 = \frac{1}{3}(x - 12) \]

  2. Distributing the \(\frac{1}{3}\): \[ y + 2 = \frac{1}{3}x - 4 \]

  3. Now isolate \(y\): \[ y = \frac{1}{3}x - 4 - 2 \] \[ y = \frac{1}{3}x - 6 \]

Now that we have the equation of the line in slope-intercept form (\(y = \frac{1}{3}x - 6\)), we can substitute the x-coordinates of each given point to see if the corresponding y-values match.

Check each option:

  1. Option (−12, 2) and (−9, 3):

    • For \(x = -12\): \[ y = \frac{1}{3}(-12) - 6 = -4 - 6 = -10 \quad (\text{not } 2) \]
    • For \(x = -9\): \[ y = \frac{1}{3}(-9) - 6 = -3 - 6 = -9 \quad (\text{not } 3) \]
  2. Option (12, -2) and (13, 1):

    • For \(x = 12\): \[ y = \frac{1}{3}(12) - 6 = 4 - 6 = -2 \quad (\text{correct!}) \]
    • For \(x = 13\): \[ y = \frac{1}{3}(13) - 6 \approx 4.33 - 6 = -1.67 \quad (\text{not } 1) \]
  3. Option (12, -2) and (15, -1):

    • For \(x = 12\): \[ y = \frac{1}{3}(12) - 6 = 4 - 6 = -2 \quad (\text{correct!}) \]
    • For \(x = 15\): \[ y = \frac{1}{3}(15) - 6 = 5 - 6 = -1 \quad (\text{correct!}) \]
  4. Option (−12, 2) and (−11, 3):

    • For \(x = -12\): \[ y = \frac{1}{3}(-12) - 6 = -10 \quad (\text{not } 2) \]
    • For \(x = -11\): \[ y = \frac{1}{3}(-11) - 6 \approx -3.67 - 6 = -9.67 \quad (\text{not } 3) \]

Conclusion:

The only correct option where both points lie on the line is (12, −2) and (15, −1).