Math Problem Statement

Use the graph to determine the following limits and values: (a) lim_{x → 3^-} g(x) (b) lim_{x → 3^+} g(x) (c) lim_{x → 3} g(x) (d) g(-3) (e) lim_{x → 0} (2f(x) + g(x)) (f) lim_{x → 3} f(g(x))

Solution

Let's begin by analyzing the information given in the picture and solve each question step by step.

Graph Observations:

  • The red curve is f(x)f(x).
  • The blue curve is g(x)g(x).
  • Solid dots indicate the values where the function is defined, while hollow dots represent holes (undefined values at those points).
  • The axes help us approximate the behavior of the functions around the specified points.

Solving the Problems:

(a) limx3g(x)\lim_{x \to 3^-} g(x)

We are looking for the left-hand limit of g(x)g(x) as xx approaches 3.

  • As x3x \to 3^- (from the left), the blue curve appears to approach a value slightly below 00.
  • Answer: limx3g(x)=1\lim_{x \to 3^-} g(x) = -1.

(b) limx3+g(x)\lim_{x \to 3^+} g(x)

We are now looking for the right-hand limit of g(x)g(x) as xx approaches 3.

  • As x3+x \to 3^+ (from the right), the blue curve approaches 1-1.
  • Answer: limx3+g(x)=1\lim_{x \to 3^+} g(x) = -1.

(c) limx3g(x)\lim_{x \to 3} g(x)

The overall limit at x=3x = 3 exists if both the left-hand and right-hand limits are equal.

  • Since both the left-hand and right-hand limits equal 1-1, the limit exists and is 1-1.
  • Answer: limx3g(x)=1\lim_{x \to 3} g(x) = -1.

(d) g(3)g(-3)

We need to find the value of g(x)g(x) at x=3x = -3.

  • At x=3x = -3, the blue curve has a solid dot at y=1y = -1, indicating that the value of g(3)g(-3) is 1-1.
  • Answer: g(3)=1g(-3) = -1.

(e) limx0(2f(x)+g(x))\lim_{x \to 0} (2f(x) + g(x))

We need to compute the limit of the expression 2f(x)+g(x)2f(x) + g(x) as x0x \to 0.

  • From the graph:
    • As x0x \to 0, f(x)0f(x) \to 0 (since the red curve touches the origin).
    • As x0x \to 0, g(x)1g(x) \to 1 (from the blue curve).
  • Now, using these limits: limx0(2f(x)+g(x))=2×0+1=1\lim_{x \to 0} (2f(x) + g(x)) = 2 \times 0 + 1 = 1
  • Answer: limx0(2f(x)+g(x))=1\lim_{x \to 0} (2f(x) + g(x)) = 1.

(f) limx3f(g(x))\lim_{x \to 3} f(g(x))

We need to find the limit of f(g(x))f(g(x)) as x3x \to 3.

  • From part (c), we know that limx3g(x)=1\lim_{x \to 3} g(x) = -1.
  • Now we need to evaluate f(x)f(x) as x1x \to -1:
    • From the graph, f(1)=0f(-1) = 0 (since the red curve touches the x-axis at x=1x = -1).
  • Therefore: limx3f(g(x))=f(limx3g(x))=f(1)=0\lim_{x \to 3} f(g(x)) = f(\lim_{x \to 3} g(x)) = f(-1) = 0
  • Answer: limx3f(g(x))=0\lim_{x \to 3} f(g(x)) = 0.

Let me know if you need more details on any of the solutions! Here are 5 related questions that can extend the learning:

  1. How would the limit limx0f(x)\lim_{x \to 0} f(x) differ if there was a hole at x=0x = 0 in f(x)f(x)?
  2. What is the significance of left-hand and right-hand limits when analyzing a piecewise function?
  3. Can you find limx3+g(x)\lim_{x \to -3^+} g(x) using the graph?
  4. How does the composition of functions, like f(g(x))f(g(x)), behave when the inner function has discontinuities?
  5. How would you use algebraic techniques to confirm a limit value if the graph was not available?

Tip: When calculating limits, always check if the limit exists from both sides (left-hand and right-hand). If they differ, the limit does not exist at that point!

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Math Problem Analysis

Mathematical Concepts

Limits
Continuity
Functions
Piecewise Functions
Composition of Functions

Formulas

lim_{x → a^-} f(x)
lim_{x → a^+} f(x)
lim_{x → a} f(x)
Composition of functions: f(g(x))

Theorems

Limit definition
Continuity at a point

Suitable Grade Level

Grades 10-12