Math Problem Statement

Given the function f(x) = |9 - 3x| / (x - 3), determine which of the following statements about limits and the value of the function at x = 3 are true.

Solution

The function in the problem is given as:

f(x)=93xx3f(x) = \frac{|9 - 3x|}{x - 3}

The problem asks which statements are true, and these statements involve limits and the value of the function at x=3x = 3. Let's analyze the behavior of the function step by step.

Step 1: Analyzing the function and its behavior near x=3x = 3

We need to break down the absolute value:

  • For x>3x > 3, 93x<09 - 3x < 0, so 93x=(93x)=3x9|9 - 3x| = -(9 - 3x) = 3x - 9.
  • For x<3x < 3, 93x>09 - 3x > 0, so 93x=93x|9 - 3x| = 9 - 3x.

Thus, we have two cases:

  • For x>3x > 3, f(x)=3x9x3=3f(x) = \frac{3x - 9}{x - 3} = 3.
  • For x<3x < 3, f(x)=93xx3=3f(x) = \frac{9 - 3x}{x - 3} = -3.

Step 2: Evaluating the limit as x3x \to 3

  • For x3+x \to 3^+, f(x)=3f(x) = 3.
  • For x3x \to 3^-, f(x)=3f(x) = -3.

Since the left-hand limit (x3x \to 3^-) and the right-hand limit (x3+x \to 3^+) are not equal, the limit as x3x \to 3 does not exist.

Step 3: Checking f(3)f(3)

At x=3x = 3, the function is undefined because it results in a division by zero. Hence, f(3)f(3) does not exist.

Step 4: Analyzing the statements

Let's evaluate the given statements based on our analysis:

  • (a) limx3+f(x)=3\lim_{x \to 3^+} f(x) = -3 — False, as limx3+f(x)=3\lim_{x \to 3^+} f(x) = 3.
  • (b) limx0+f(x)=3\lim_{x \to 0^+} f(x) = 3 — Irrelevant, as the function does not involve behavior as x0x \to 0.
  • (c) f(3)f(3) does not exist — True, since f(3)f(3) results in division by zero.
  • (d) limx3f(x)=3\lim_{x \to 3^-} f(x) = -3 — True, as limx3f(x)=3\lim_{x \to 3^-} f(x) = -3.
  • (e) limx3f(x)\lim_{x \to 3} f(x) exists — False, since the limits from the left and right do not match.
  • (f) limx3f(x)\lim_{x \to 3} f(x) does not exist — True, since the left and right limits are not equal.
  • (g) limx3f(x)=3\lim_{x \to 3} f(x) = 3 — False, as the limit does not exist.
  • (h) limx3+f(x)=3\lim_{x \to 3^+} f(x) = 3 — True, since limx3+f(x)=3\lim_{x \to 3^+} f(x) = 3.

Final Answer:

The correct statements are (c), (d), (f), and (h).


Would you like more details on any part of the solution? Here are 5 related questions you can explore:

  1. How do you handle absolute value functions when calculating limits?
  2. What are the conditions for a limit to exist at a point?
  3. Why does division by zero make a function undefined?
  4. What is the difference between left-hand and right-hand limits?
  5. How does the behavior of a function change around a point of discontinuity?

Tip: When evaluating limits, always consider the left-hand and right-hand limits separately to check for discontinuities.

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Math Problem Analysis

Mathematical Concepts

Limits
Absolute Value
Continuity
Discontinuity

Formulas

f(x) = |9 - 3x| / (x - 3)
Limit calculation: left-hand and right-hand limits

Theorems

Limit Definition
Continuity at a Point
Discontinuity and Limits

Suitable Grade Level

Grade 11-12