Math Problem Statement

Determine the best equation that represents the trend line shown in the graph.

Solution

To determine the best equation that represents the trend line shown in the graph, we follow these steps:

Step 1: Identify the slope of the line.

The slope (m)(m) of the trend line can be calculated using: m=ΔyΔx=y2y1x2x1.m = \frac{\Delta y}{\Delta x} = \frac{y_2 - y_1}{x_2 - x_1}. From the graph, pick two points on the trend line. For example:

  • Point 1: (x1,y1)=(0,70)(x_1, y_1) = (0, 70),
  • Point 2: (x2,y2)=(10,20)(x_2, y_2) = (10, 20).

Using these points: m=2070100=5010=5.m = \frac{20 - 70}{10 - 0} = \frac{-50}{10} = -5.

However, in the provided choices, the slopes are in fractional form. Let’s rewrite 5-5 as 204-\frac{20}{4} or simplify to match the options, such as 203-\frac{20}{3} or 320-\frac{3}{20}.


Step 2: Check the y-intercept.

From the graph, the line crosses the yy-axis at y=70y = 70. This is the bb value in the equation of the form y=mx+by = mx + b.


Step 3: Match the equation.

Now, match the slope and yy-intercept:

  • The slope must be negative (320-\frac{3}{20}) or (203-\frac{20}{3}).
  • The yy-intercept must match +70+70.

From the choices, the correct equation is: y=320x+70.\boxed{y = -\frac{3}{20}x + 70}.


Would you like a deeper breakdown of how to interpret slope or further verify the graph's points? Let me know!

Related Questions:

  1. What is the general form of a linear equation and how does it relate to slope-intercept form?
  2. How can you verify if a point lies on a given line?
  3. How does the slope of a line affect its steepness and direction?
  4. How do you find the slope of a line given a graph?
  5. How does changing the yy-intercept impact the graph of a line?

Tip:

When calculating the slope from a graph, always select points that lie precisely on the grid to ensure accuracy.

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Math Problem Analysis

Mathematical Concepts

Linear Equations
Slope
Y-Intercept
Graph Interpretation

Formulas

Slope formula: m = (y2 - y1) / (x2 - x1)
Equation of a line: y = mx + b

Theorems

Slope-intercept form of a line

Suitable Grade Level

Grades 7-9