The table below represents ordered pairs for a linear function.

x ----- y
-1 ---- 3.5
0 ------ 4
1 ----- 4.5
2 ------ 5

Which graph represents this linear function?

Responses
A. A graph labeled "A" displays a straight red line that extends from the lower-left quadrant to the upper-right quadrant. The line slopes upward. The x-axis extends from -5 to 5 and the y-axis extends from -5 to 5. The graph is a coordinate plane, with evenly spaced grid lines marking the axes. The line passes through the points (-2, 2) and (3, 5) approximately.

C. A graph, labeled C, displays a straight red line. The line passes through the points (1, 0) and (2, 5) and extends beyond these points in both directions. 

The x-axis ranges from -5 to 5, with each grid mark representing one unit. The y-axis ranges from -5 to 5, also with each grid mark representing one unit. The graph is on a grid with equally spaced lines, indicating a coordinate plane.

B. A graph, labeled B, displays a straight red line.

The line passes through points (-2, 0) and (4, 5), and extends beyond these points.

The x-axis ranges from -5 to 5, and the y-axis also ranges from -5 to 5. The grid is a standard coordinate graph with evenly spaced tick marks.

D. A graph labeled "D" is shown. 

The x-axis ranges from -5 to 5, and the y-axis from -4 to 5.

A straight red line is drawn, sloping downwards from the top left to the bottom right. The line extends beyond the visible portion of the graph. There are gridlines to aid in visualizing coordinate points and the slope. The line has a negative slope.

1 answer

To determine which graph represents the given linear function, we first need to find the slope and y-intercept of the function using the provided ordered pairs. Let's analyze the points:

The ordered pairs are:

  • (-1, 3.5)
  • (0, 4)
  • (1, 4.5)
  • (2, 5)

From the points above, we can calculate the slope \( m \) using the formula:

\[ m = \frac{y_2 - y_1}{x_2 - x_1} \]

Using two points, for example (0, 4) and (1, 4.5):

\[ m = \frac{4.5 - 4}{1 - 0} = \frac{0.5}{1} = 0.5 \]

Now we need to find the y-intercept \( b \). Since the point (0, 4) indicates that when \( x = 0 \), \( y = 4 \), we can directly state that:

\[ b = 4 \]

Thus, the equation of the line representing this linear function is:

\[ y = 0.5x + 4 \]

Next, we can verify a few points to ensure the accuracy of this equation:

  • For \( x = -1 \): \[ y = 0.5(-1) + 4 = -0.5 + 4 = 3.5 \] (matches the point)

  • For \( x = 1 \): \[ y = 0.5(1) + 4 = 0.5 + 4 = 4.5 \] (matches the point)

  • For \( x = 2 \): \[ y = 0.5(2) + 4 = 1 + 4 = 5 \] (matches the point)

The function is linear, with a positive slope of 0.5 and a y-intercept of 4, meaning the line will slope upwards.

Now let's analyze the options given for the graph:

  • Graph A: It has an upward slope and roughly agrees with the calculated values. It passes through (3, 5) which is not in our points but could be correct.

  • Graph B: This does not match as the slope appears steeper than 0.5.

  • Graph C: This has an upward slope but the points it claims to pass (1, 0) and (2, 5) do not align with our function.

  • Graph D: This has a downward slope, which is incorrect based on our function.

From this analysis, the best match seems to be Graph A, which features an upward slope which is consistent with the linear function we've derived.