Responder
(a) The domain of the function \( f \) is all real numbers, written as \( (-\infty, \infty) \).
(b) The only intercept is the y-intercept at (0, 3). There are no x-intercepts.
(c) The graph consists of two straight lines:
- For \( x < 1 \): \( y = -2x + 3 \) (open circle at (1, 1))
- For \( x \geq 1 \): \( y = 2x - 1 \) (closed dot at (1, 1))
(d) The range of the function is all real numbers greater than or equal to 1, written as \( [1, \infty) \).
Solución
We are given the piecewise function
f(x) = { –2x + 3 if x < 1
2x – 1 if x ≥ 1 }
Let’s work through each part.
─────────────────────────────
(a) Domain
Both pieces of the function have formulas defined for all x-values in their respective regions. Since every real number falls into one of these intervals, the domain of f is
(–∞, ∞).
─────────────────────────────
(b) Intercepts
Intercepts include any x-intercepts (where f(x) = 0) and the y-intercept (where x = 0).
1. Y-intercept:
Set x = 0. Since 0 < 1, we use the first piece.
f(0) = –2(0) + 3 = 3.
Thus, the y-intercept is (0, 3).
2. X-intercepts:
We need to solve f(x) = 0 in each region.
• For x < 1: Solve –2x + 3 = 0
–2x = –3 ⇒ x = 3/2 = 1.5.
But 1.5 is not less than 1, so this solution does not belong to the first piece.
• For x ≥ 1: Solve 2x – 1 = 0
2x = 1 ⇒ x = 1/2 = 0.5.
However, 0.5 is not in the domain x ≥ 1.
Since neither branch provides an acceptable x-value, there are no x-intercepts.
Thus, the only intercept is the y-intercept (0, 3).
─────────────────────────────
(c) Graph of the Function
1. For x < 1, the function f(x) = –2x + 3 is a straight line with a slope of –2 and a y-intercept of 3.
• When x is very small (large negative), f(x) is large positive.
• As x approaches 1 from the left, f(1⁻) = –2(1) + 3 = 1.
• Note: The point (1, 1) is not included in this piece (open circle at (1, 1)).
2. For x ≥ 1, the function f(x) = 2x – 1 is also a straight line, with a slope of 2.
• At x = 1, f(1) = 2(1) – 1 = 1, so the graph includes the point (1, 1) (closed dot).
• As x increases, f(x) increases linearly.
The overall graph consists of two ray segments that meet at (1, 1); the left piece approaches (1, 1) with an open circle, while the right piece starts at (1, 1) with a closed circle.
─────────────────────────────
(d) Range
To find the range, notice the following:
• For x ≥ 1: f(x) = 2x – 1 is an increasing line. Its minimum value is at x = 1, giving f(1) = 1, and f(x) increases without bound as x increases.
• For x < 1: f(x) = –2x + 3 is a decreasing function as x increases toward 1. As x approaches 1 from the left, f(x) approaches 1 from above. For x very negative, f(x) becomes very large.
Thus, the smallest value that f actually takes is f(1) = 1, and all values greater than or equal to 1 are attained.
Therefore, the range is
[1, ∞).
─────────────────────────────
Summary Answers
(a) Domain: (–∞, ∞)
(b) Intercepts:
• Y-intercept: (0, 3)
• No x-intercepts
(c) Graph: Two line segments—one for x < 1 given by y = –2x + 3 (with an open circle at (1, 1)) and one for x ≥ 1 given by y = 2x – 1 (starting with a closed dot at (1, 1)).
(d) Range: [1, ∞)
Respondido por UpStudy AI y revisado por un tutor profesional

Explicar

Simplifique esta solución