Math Problem Statement

Write the equation of the line in fully simplified slope-intercept form.

Solution

To find the equation of the line in fully simplified slope-intercept form, y=mx+by = mx + b, we need two key pieces of information from the graph: the slope (mm) and the y-intercept (bb).

Step 1: Identify two points on the line

Looking at the graph, two clear points on the line are:

  • (0,7)(0, 7) (the y-intercept),
  • (4,2)(4, -2).

Step 2: Calculate the slope (mm)

The formula for the slope is:

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

Substitute the coordinates of the points (0,7)(0, 7) and (4,2)(4, -2):

m=2740=94m = \frac{{-2 - 7}}{{4 - 0}} = \frac{{-9}}{{4}}

So, the slope m=94m = -\frac{9}{4}.

Step 3: Identify the y-intercept (bb)

From the graph, the line crosses the y-axis at y=7y = 7, so b=7b = 7.

Step 4: Write the equation

Now that we have the slope and y-intercept, we can write the equation of the line:

y=94x+7y = -\frac{9}{4}x + 7

This is the fully simplified equation of the line in slope-intercept form.

Would you like more details or have any questions?

Here are 5 related questions to expand this topic:

  1. How do you calculate the slope if you are given two points on a line?
  2. What does the slope of a line tell you about its steepness and direction?
  3. How can you find the equation of a line if you only know the slope and one point on the line?
  4. What happens to the slope-intercept form if the line is vertical or horizontal?
  5. How would the graph change if the slope were positive instead of negative?

Tip: To find the slope of any line from a graph, always pick two points that are easy to identify, such as points where the line crosses grid lines exactly.

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Math Problem Analysis

Mathematical Concepts

Algebra
Coordinate Geometry

Formulas

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

Theorems

Line equation theorem

Suitable Grade Level

Grades 7-10