Math Problem Statement

The x-intercept of a line is 8 and its y-intercept is 4. Which equation represents the line?

Solution

To solve this problem, we can determine the equation of a line using the given intercepts:

  • The x-intercept is 8, meaning the point (8,0)(8, 0) lies on the line.
  • The y-intercept is 4, meaning the point (0,4)(0, 4) lies on the line.

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

y=mx+by = mx + b

Where:

  • mm is the slope
  • bb is the y-intercept (which is already given as 4)

Step 1: Calculate the slope

The slope mm is calculated using the formula:

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

Using the points (8,0)(8, 0) and (0,4)(0, 4):

m=4008=48=12m = \frac{4 - 0}{0 - 8} = \frac{4}{-8} = -\frac{1}{2}

Step 2: Write the equation

Now that we know the slope m=12m = -\frac{1}{2} and the y-intercept is 4, we can write the equation as:

y=12x+4y = -\frac{1}{2}x + 4

Step 3: Match with the given options

This matches Option C, which is:

y=12x+4y = -\frac{1}{2}x + 4

Thus, the correct answer is C.

Would you like further explanation on any part? Here are five related questions to deepen your understanding:

  1. How do you find the slope of a line given two points?
  2. Can you derive the equation of a line if only one point and the slope are given?
  3. What is the significance of the y-intercept in the slope-intercept form?
  4. How can we find the x-intercept of a line if only the equation is given?
  5. How does the sign of the slope affect the graph of the line?

Tip: When finding the slope, always ensure to subtract the coordinates in the same order (e.g., y2y1y_2 - y_1 and x2x1x_2 - x_1).

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Equations

Formulas

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

Theorems

Slope-Intercept Theorem

Suitable Grade Level

Grades 8-10