Math Problem Statement

Suppose that f and g are continuous functions such that f(3) = 6 and lim(x→3) [f(x) + 8g(x)] = 19. Calculate the following: (a) lim(x→3) f(x) (b) lim(x→3) g(x) (c) g(3)

Solution

Let's analyze the problem step by step based on the given information:

Given Information:

  1. ff and gg are continuous functions.
  2. f(3)=6f(3) = 6.
  3. limx3[f(x)+8g(x)]=19\lim_{x \to 3} \left[ f(x) + 8g(x) \right] = 19.

We are asked to compute:

  • (a) limx3f(x)\lim_{x \to 3} f(x)
  • (b) limx3g(x)\lim_{x \to 3} g(x)
  • (c) g(3)g(3)

Step 1: Understanding continuity

Since ff and gg are continuous at x=3x = 3, this implies: limx3f(x)=f(3)=6\lim_{x \to 3} f(x) = f(3) = 6 Thus, part (a) is straightforward:

(a) limx3f(x)=6\lim_{x \to 3} f(x) = 6

Step 2: Using the given limit

We are given that: limx3[f(x)+8g(x)]=19\lim_{x \to 3} \left[ f(x) + 8g(x) \right] = 19 Since limits distribute over addition, we can break this into two parts: limx3f(x)+8limx3g(x)=19\lim_{x \to 3} f(x) + 8 \lim_{x \to 3} g(x) = 19 Substitute limx3f(x)=6\lim_{x \to 3} f(x) = 6 into the equation: 6+8limx3g(x)=196 + 8 \lim_{x \to 3} g(x) = 19 Solve for limx3g(x)\lim_{x \to 3} g(x): 8limx3g(x)=1968 \lim_{x \to 3} g(x) = 19 - 6 8limx3g(x)=138 \lim_{x \to 3} g(x) = 13 limx3g(x)=138\lim_{x \to 3} g(x) = \frac{13}{8}

Thus, (b) limx3g(x)=138\lim_{x \to 3} g(x) = \frac{13}{8}.

Step 3: Continuity of g(x)g(x)

Since g(x)g(x) is continuous, we have: g(3)=limx3g(x)g(3) = \lim_{x \to 3} g(x) Thus, (c) g(3)=138g(3) = \frac{13}{8}.

Final Answers:

  • (a) limx3f(x)=6\lim_{x \to 3} f(x) = 6
  • (b) limx3g(x)=138\lim_{x \to 3} g(x) = \frac{13}{8}
  • (c) g(3)=138g(3) = \frac{13}{8}

Would you like further details or have any other questions?

Here are five related questions to expand this topic:

  1. What are the properties of continuous functions that help solve limits?
  2. How can we apply the epsilon-delta definition to prove continuity at a point?
  3. Can discontinuous functions have limits that exist?
  4. How does continuity of a sum of functions affect their individual limits?
  5. How do we interpret limits at infinity for continuous functions?

Tip: Always check for continuity when dealing with limits at specific points—it simplifies solving limits.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Limits
Continuity
Algebraic Manipulation

Formulas

lim(x→c) [f(x) + g(x)] = lim(x→c) f(x) + lim(x→c) g(x)

Theorems

Continuity of a Function
Properties of Limits

Suitable Grade Level

Grades 11-12