Use the image to answer the question.

A descending curve is graphed in quadrant 1 of a coordinate plane. The points left parenthesis 1 comma 14 right parenthesis and left parenthesis 2 comma 4 right parenthesis are plotted on the curve. The curve descends to but does not cross the x-axis.

Given the graph of the exponential equation, which option is the correct exponential equation for the graph?

Option #1: y=7(1/2)^x

Option #2: y=49(2/7)^x

Option #3: y=7(2/7)^x

Option #4: y=49(7/2)^x

(1 point)
Option #_
is the correct equation for the graph.

1 answer

To determine which of the given options is the correct exponential equation for the graph based on the points plotted and the information provided, we can evaluate each option with the coordinates provided in the points (1, 14) and (2, 4).

  1. Option #1: \( y = 7\left(\frac{1}{2}\right)^x \)

    • For \( x = 1 \): \( y = 7\left(\frac{1}{2}\right)^1 = 7 \times \frac{1}{2} = 3.5 \) (not 14)
    • For \( x = 2 \): \( y = 7\left(\frac{1}{2}\right)^2 = 7 \times \frac{1}{4} = 1.75 \) (not 4)
  2. Option #2: \( y = 49\left(\frac{2}{7}\right)^x \)

    • For \( x = 1 \): \( y = 49\left(\frac{2}{7}\right)^1 = 49 \times \frac{2}{7} = 14 \) (correct)
    • For \( x = 2 \): \( y = 49\left(\frac{2}{7}\right)^2 = 49 \times \frac{4}{49} = 4 \) (correct)
  3. Option #3: \( y = 7\left(\frac{2}{7}\right)^x \)

    • For \( x = 1 \): \( y = 7\left(\frac{2}{7}\right)^1 = 7 \times \frac{2}{7} = 2 \) (not 14)
    • For \( x = 2 \): \( y = 7\left(\frac{2}{7}\right)^2 = 7 \times \frac{4}{49} = \frac{28}{49} = \frac{4}{7} \) (not 4)
  4. Option #4: \( y = 49\left(\frac{7}{2}\right)^x \)

    • For \( x = 1 \): \( y = 49\left(\frac{7}{2}\right)^1 = 49 \times \frac{7}{2} = 171.5 \) (not 14)
    • For \( x = 2 \): \( y = 49\left(\frac{7}{2}\right)^2 = 49 \times \frac{49}{4} = 600.25 \) (not 4)

Based on the evaluations, Option #2 is the only one that correctly matches the points (1, 14) and (2, 4).

Therefore, the answer is: Option #2 is the correct equation for the graph.