Math Problem Statement

A student created this table to represent a linear relationship between x and y. Based on the table, answer the following: (a) What is the y-intercept of the line represented by the x and y values shown? (b) What is the slope of the line represented by the x and y values shown? (c) Write an equation of the line represented by the relationship between x and y shown in the table. (d) The student says the point (9, -17.5) lies on the line represented by the relationship between x and y shown in the table. Is the student correct? Show or explain how you got your answer.

Solution

Let's analyze the questions step-by-step based on the image.

Given Table:

xy
-2-10.0
-1-7.5
0-5.0
1-2.5
20.0

Part A: Finding the y-intercept

The y-intercept is the y-value when x=0x = 0. From the table, when x=0x = 0, y=5.0y = -5.0.

  • Answer for Part A: The y-intercept is -5.0.

Part B: Calculating the Slope

The slope (m) of a linear relationship can be found using the formula: m=y2y1x2x1m = \frac{{y_2 - y_1}}{{x_2 - x_1}} Using two points from the table, such as (2,10.0)(-2, -10.0) and (0,5.0)(0, -5.0): m=5.0(10.0)0(2)=5.02=2.5m = \frac{-5.0 - (-10.0)}{0 - (-2)} = \frac{5.0}{2} = 2.5

  • Answer for Part B: The slope of the line is 2.5.

Part C: Writing the Equation of the Line

Using the slope-intercept form y=mx+by = mx + b, where m=2.5m = 2.5 and b=5.0b = -5.0, the equation becomes: y=2.5x5.0y = 2.5x - 5.0

  • Answer for Part C: The equation of the line is y=2.5x5.0y = 2.5x - 5.0.

Part D: Verifying a Point on the Line

The student claims that the point (9,17.5)(9, -17.5) lies on the line. To verify, substitute x=9x = 9 into the equation: y=2.5×95.0=22.55.0=17.5y = 2.5 \times 9 - 5.0 = 22.5 - 5.0 = 17.5 The calculated y-value is 17.517.5, not 17.5-17.5, so the point (9,17.5)(9, -17.5) does not lie on the line.

  • Answer for Part D: The student is incorrect.

Would you like further details on any part?

Here are some related questions for deeper understanding:

  1. How do you determine the y-intercept from a table?
  2. Can you find the slope using any two points on a linear line?
  3. Why is it essential to use the slope-intercept form to write the equation of a line?
  4. How can you verify if a point lies on a line using the line’s equation?
  5. What happens to the line if the slope or y-intercept changes?

Tip: When verifying if a point lies on a line, substitute both x and y into the equation to check for equality.

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Math Problem Analysis

Mathematical Concepts

Linear Relationships
Slope-Intercept Form
Point Verification

Formulas

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

Theorems

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Suitable Grade Level

Grades 8-10