Math Problem Statement

The function f is defined as follows: f(x) = -2x + 3 for x < 1; 4x - 3 for x ≥ 1. (a) Find the domain of the function. (b) Locate any intercepts. (c) Graph the function. (d) Based on the graph, find the range.

Solution

Let's go step by step through each part of the problem involving the piecewise function f(x)f(x):

  1. Given Function: \begin{cases} -2x + 3 & \text{if } x < 1 \\ 4x - 3 & \text{if } x \geq 1 \end{cases}$$

(a) Find the domain of the function.

The domain of a function is the set of all possible input values (x-values). In this case:

  • For x<1x < 1, the function is 2x+3-2x + 3, which is valid for all xx less than 1.
  • For x1x \geq 1, the function is 4x34x - 3, which is valid for all xx greater than or equal to 1.

Thus, the domain of the function is all real numbers: Domain: (,)\text{Domain: } (-\infty, \infty)

(b) Locate any intercepts.

i) x-intercept:

To find the x-intercept, we set f(x)=0f(x) = 0 and solve for xx.

  • For x<1x < 1 (using f(x)=2x+3f(x) = -2x + 3): 2x+3=0    x=32=1.5-2x + 3 = 0 \implies x = \frac{3}{2} = 1.5 But this is outside the valid range of x<1x < 1, so there is no x-intercept in this case.

  • For x1x \geq 1 (using f(x)=4x3f(x) = 4x - 3): 4x3=0    x=34=0.754x - 3 = 0 \implies x = \frac{3}{4} = 0.75 Since x=0.75x = 0.75 is less than 1, it doesn't fit the range of x1x \geq 1, so there is no x-intercept in this case.

ii) y-intercept:

To find the y-intercept, set x=0x = 0 and find f(0)f(0).

Since 0<10 < 1, we use f(x)=2x+3f(x) = -2x + 3: f(0)=2(0)+3=3f(0) = -2(0) + 3 = 3

Thus, the y-intercept is (0,3)(0, 3).

(c) Graph the function.

To graph the function:

  • For x<1x < 1, plot the line f(x)=2x+3f(x) = -2x + 3, which has a y-intercept of 3 and a slope of -2.
  • For x1x \geq 1, plot the line f(x)=4x3f(x) = 4x - 3, which starts at x=1x = 1 and has a slope of 4.

At x=1x = 1:

  • f(1)=4(1)3=1f(1) = 4(1) - 3 = 1. So, there is a point at (1,1)(1, 1).

The graph will show two distinct lines: one line before x=1x = 1 and another starting from x=1x = 1.

(d) Based on the graph, find the range.

The range is the set of all possible output values (y-values). Based on the two parts of the function:

  • For x<1x < 1, the function 2x+3-2x + 3 decreases without bound as xx \to -\infty, so the lower limit of the range is -\infty.
  • For x1x \geq 1, the function 4x34x - 3 increases without bound as xx \to \infty.

The range of the function is: Range: (,)\text{Range: } (-\infty, \infty)


Do you need more details on any part of the solution? Here are some related questions to further explore this topic:

  1. What happens to the graph of the function as xx \to \infty?
  2. How do you calculate the slope of a linear function?
  3. What is the significance of discontinuity in a piecewise function like this one?
  4. How can you check if the piecewise function is continuous at x=1x = 1?
  5. Can there be more than one y-intercept in a piecewise function?

Tip: When graphing piecewise functions, always check for continuity and whether the function's values match at the boundaries between intervals.

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Math Problem Analysis

Mathematical Concepts

Piecewise Functions
Domain and Range
Intercepts
Graphing Linear Functions

Formulas

Linear equation f(x) = mx + b
Domain of a piecewise function
Range of a piecewise function

Theorems

Slope-Intercept Formula
Definition of Domain and Range

Suitable Grade Level

Grades 10-12