Math Problem Statement

Which equation is best represented by the graph?

Solution

To solve this problem, let's analyze the graph and compare it to the given options.

The equation of a straight line is usually written in slope-intercept form, which is:

y=mx+by = mx + b

Where:

  • mm is the slope of the line.
  • bb is the y-intercept (the point where the line crosses the y-axis).

Step 1: Find the slope (m)

From the graph, the line moves downward, indicating a negative slope. We can find the slope by calculating the "rise" over "run" between two points on the line. Let's choose two points:

  • The line crosses through the point (5,0)(-5, 0) and (0,2)(0, -2).
  • Slope formula:

m=y2y1x2x1=200(5)=25m = \frac{y_2 - y_1}{x_2 - x_1} = \frac{-2 - 0}{0 - (-5)} = \frac{-2}{5}

So the slope is m=13m = -\frac{1}{3}.

Step 2: Find the y-intercept (b)

The y-intercept is where the line crosses the y-axis, which from the graph is y=2y = -2.

Step 3: Write the equation

Using the slope-intercept form y=mx+by = mx + b with m=13m = -\frac{1}{3} and b=2b = -2, the equation of the line is:

y=13x2y = -\frac{1}{3}x - 2

Step 4: Compare to the options

We need to rewrite this in point-slope form to match the answer choices, which are in the format:

yy1=m(xx1)y - y_1 = m(x - x_1)

From the graph, we see the line passes through (5,0)(-5, 0), and substituting into point-slope form gives us:

y+2=13(x+5)y + 2 = -\frac{1}{3}(x + 5)

Answer:

The correct answer is the first option: y+2=13(x+5)y + 2 = -\frac{1}{3}(x + 5)

Do you have any questions or want further details? Here are 5 related questions you might want to explore:

  1. How do you convert between slope-intercept form and point-slope form?
  2. What are the steps to find the slope of a line from a graph?
  3. How can you determine the y-intercept just by looking at the graph?
  4. How do you know when to use point-slope form versus slope-intercept form?
  5. Can you find the equation of a line if you're only given two points?

Tip: Always pick clear points from the graph when calculating the slope to avoid errors!

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Math Problem Analysis

Mathematical Concepts

Linear Equations
Slope-Intercept Form
Point-Slope Form

Formulas

Slope formula m = (y2 - y1) / (x2 - x1)
Point-slope form y - y1 = m(x - x1)
Slope-intercept form y = mx + b

Theorems

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Suitable Grade Level

Grade 8-10