Math Problem Statement

Graph the equation y = |2x - 13| by hand. (a) Find the x-intercept. (b) Determine where the graph is increasing and where it is decreasing.

Solution

Let's solve the problem step-by-step.

Problem Analysis

  1. Given Equation: y=2x13y = |2x - 13|
  2. Tasks:
    • Find the x-intercept.
    • Determine intervals where the graph is increasing and decreasing.
    • Identify the correct graph from options A, B, C, and D.

Solution Steps

Step 1: Finding the X-Intercept

To find the x-intercept, set y=0y = 0: 0=2x130 = |2x - 13| This implies: 2x13=02x - 13 = 0 Solving for xx: x=132=6.5x = \frac{13}{2} = 6.5 So, the x-intercept is (6.5,0)(6.5, 0).

Step 2: Determine Intervals of Increase and Decrease

Since this is an absolute value function, it has a vertex (turning point) where the expression inside the absolute value equals zero: 2x13=0x=6.52x - 13 = 0 \Rightarrow x = 6.5

  • For x<6.5x < 6.5: y=132xy = 13 - 2x, which is a decreasing function as xx increases.
  • For x>6.5x > 6.5: y=2x13y = 2x - 13, which is an increasing function as xx increases.

Thus:

  • The graph is increasing on the interval (6.5,)(6.5, \infty).
  • The graph is decreasing on the interval (,6.5)(-\infty, 6.5).

Step 3: Identify the Correct Graph

From these observations:

  • The correct graph should have a vertex at (6.5,0)(6.5, 0), with the graph decreasing to the left of x=6.5x = 6.5 and increasing to the right.
  • Option A seems to match this description, with a V-shape centered at (6.5,0)(6.5, 0), decreasing on the left and increasing on the right.

Summary of Answers

  • X-intercept: (6.5,0)(6.5, 0)
  • Increasing interval: (6.5,)(6.5, \infty)
  • Decreasing interval: (,6.5)(-\infty, 6.5)
  • Correct Graph: Option A

Would you like further clarification on any of these steps?


Related Questions

  1. How do you find the x-intercept of an absolute value function in general?
  2. Why does the absolute value function create a V-shaped graph?
  3. What are other methods to determine increasing and decreasing intervals for more complex functions?
  4. How would the solution change if the function were y=3x10y = |3x - 10| instead?
  5. What transformations affect the shape and position of an absolute value graph?

Tip

Absolute value graphs form V-shapes because they mirror the linear part of the function across the x-axis when the expression inside becomes negative.

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Math Problem Analysis

Mathematical Concepts

Absolute Value Functions
Graphing
Intervals of Increase and Decrease

Formulas

Absolute value function y = |ax + b|
Finding x-intercept by setting y = 0

Theorems

Properties of absolute value functions

Suitable Grade Level

Grades 9-11