Math Problem Statement

Using f(x) = log x, what is the x-intercept of g(x) = log (x + 4)? Explain your reasoning.

Solution

To find the x-intercept of the function g(x)=log(x+4)g(x) = \log(x + 4), we need to determine the value of xx where g(x)=0g(x) = 0.

Step-by-Step Process:

  1. Set g(x)=0g(x) = 0: g(x)=log(x+4)g(x) = \log(x + 4) For the x-intercept, we set g(x)=0g(x) = 0, so: log(x+4)=0\log(x + 4) = 0

  2. Use the definition of logarithm: The logarithmic function logb(y)=x\log_b(y) = x means that bx=yb^x = y. In this case, we're working with the common logarithm (base 10), so we can rewrite the equation as: 100=x+410^0 = x + 4 Since 100=110^0 = 1, this simplifies to: 1=x+41 = x + 4

  3. Solve for xx: x=14x = 1 - 4 x=3x = -3

Conclusion:

The x-intercept of g(x)=log(x+4)g(x) = \log(x + 4) is x=3x = -3. This is the point where the graph of the function crosses the x-axis.


Would you like a more detailed explanation of logarithms or how to work with transformations? Here are some related questions you might find interesting:

  1. How does the graph of g(x)=log(x+4)g(x) = \log(x + 4) differ from the graph of f(x)=log(x)f(x) = \log(x)?
  2. How would you find the x-intercept of a logarithmic function with a different base, say base 2 or base ee?
  3. What is the domain of the function g(x)=log(x+4)g(x) = \log(x + 4)?
  4. How would you graph the function g(x)=log(x+4)g(x) = \log(x + 4)?
  5. What is the significance of the vertical asymptote in logarithmic functions?

Tip: When working with logarithmic equations, remember that logarithms are only defined for positive arguments, so always ensure that the expression inside the logarithm is greater than zero.

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Math Problem Analysis

Mathematical Concepts

Logarithms
Transformations of functions

Formulas

log(x) = 0 implies x = 1
log_b(x) = 0 implies x = b^0

Theorems

Properties of logarithms
Logarithmic transformation rules

Suitable Grade Level

Grades 9-11