Math Problem Statement

Graph the piecewise function f(x) = {-2x if x < 1, 0.5x + 1 if x ≥ 1}.

Solution

To graph the given piecewise function:

Function Definition:

  1. f(x)=2xf(x) = -2x if x<1x < 1
  2. f(x)=0.5x+1f(x) = 0.5x + 1 if x1x \geq 1

Step-by-step Procedure:

  1. For x<1x < 1:

    • This part of the function is f(x)=2xf(x) = -2x, a straight line with slope 2-2 and passing through the origin.
    • Since x<1x < 1, only plot this line for values of xx less than 1.
    • For x=1x = 1, f(x)=2(1)=2f(x) = -2(1) = -2 (not included, represented by an open circle at (1,2)(1, -2)).
  2. For x1x \geq 1:

    • This part of the function is f(x)=0.5x+1f(x) = 0.5x + 1, a straight line with slope 0.50.5 and yy-intercept at (0,1)(0, 1).
    • Since x1x \geq 1, only plot this line for values of x1x \geq 1.
    • For x=1x = 1, f(x)=0.5(1)+1=1.5f(x) = 0.5(1) + 1 = 1.5 (included, represented by a closed circle at (1,1.5)(1, 1.5)).

Plot Points:

  • For f(x)=2xf(x) = -2x (when x<1x < 1):

    • At x=0x = 0, f(x)=0f(x) = 0.
    • At x=1x = -1, f(x)=2(1)=2f(x) = -2(-1) = 2.
  • For f(x)=0.5x+1f(x) = 0.5x + 1 (when x1x \geq 1):

    • At x=1x = 1, f(x)=1.5f(x) = 1.5.
    • At x=2x = 2, f(x)=0.5(2)+1=2f(x) = 0.5(2) + 1 = 2.
    • At x=3x = 3, f(x)=0.5(3)+1=2.5f(x) = 0.5(3) + 1 = 2.5.

Notes for Graphing:

  1. Mark an open circle at (1,2)(1, -2) for f(x)=2xf(x) = -2x.
  2. Mark a closed circle at (1,1.5)(1, 1.5) for f(x)=0.5x+1f(x) = 0.5x + 1.
  3. Draw the respective lines in their domains.

Would you like a graphical representation or further clarification?

Here are some questions to expand on this concept:

  1. How can we determine if a circle at a boundary is open or closed?
  2. What does the slope of a line indicate about its behavior?
  3. How would the graph change if the conditions for xx were reversed?
  4. How do we evaluate the continuity of a piecewise function at the boundaries?
  5. What are the implications of having different slopes in the two parts of the function?

Tip: Always test the boundary point in both pieces to ensure you correctly represent its inclusion or

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Math Problem Analysis

Mathematical Concepts

Piecewise functions
Linear equations
Graphing functions

Formulas

y = mx + b (equation of a line)
Piecewise function definition

Theorems

Continuity and inclusion/exclusion of boundary points

Suitable Grade Level

Grades 8-10