Math Problem Statement

What is an equation of the line?

What is an equation of the line?

Solution

To find the equation of the line from the graph, we need to determine two things:

  1. The slope (mm): This is the rate at which the line rises or falls. It is calculated as the ratio of the change in yy to the change in xx between two points on the line.
  2. The y-intercept (bb): This is the point where the line crosses the y-axis (when x=0x = 0).

Step 1: Identify two points on the line.

From the graph, we can pick two points that the line passes through:

  • (2,0)(-2, 0)
  • (4,3)(4, -3)

Step 2: Calculate the slope.

The slope mm is given by the formula:

m=y2y1x2x1m = \frac{{y_2 - y_1}}{{x_2 - x_1}}

Using the points (2,0)(-2, 0) and (4,3)(4, -3): m=304(2)=34+2=36=12m = \frac{{-3 - 0}}{{4 - (-2)}} = \frac{{-3}}{{4 + 2}} = \frac{{-3}}{{6}} = -\frac{1}{2}

Step 3: Use the slope-intercept form.

The equation of a line in slope-intercept form is:

y=mx+by = mx + b

We know m=12m = -\frac{1}{2}. Now, to find bb, we can use one of the points. Let's use (2,0)(-2, 0):

0=12(2)+b0 = -\frac{1}{2}(-2) + b 0=1+b    b=10 = 1 + b \implies b = -1

Final Equation:

Thus, the equation of the line is:

y=12x1y = -\frac{1}{2}x - 1

Would you like more details or have any questions about this? Here are some related questions for deeper understanding:

  1. How do you calculate the slope from different pairs of points?
  2. What is the significance of the y-intercept in a graph?
  3. How would the equation change if the slope were positive?
  4. Can you find the equation of a line using point-slope form?
  5. How can the slope-intercept form be derived from the standard form of a line?

Tip: Always use clear points from the graph to ensure accuracy when calculating the slope and intercept.

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Math Problem Analysis

Mathematical Concepts

Algebra
Coordinate Geometry
Linear Equations

Formulas

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

Theorems

Slope of a line
Slope-intercept form theorem

Suitable Grade Level

Grades 8-10