Math Problem Statement

f(x)=\log_{2}(-x)-4 how to find the x-intercept

Solution

To find the xx-intercept of the function f(x)=log2(x)4f(x) = \log_{2}(-x) - 4, you set f(x)=0f(x) = 0 and solve for xx. Here's how:

  1. Set f(x)=0f(x) = 0: 0=log2(x)40 = \log_{2}(-x) - 4

  2. Isolate the logarithmic term: log2(x)=4\log_{2}(-x) = 4

  3. Rewrite the logarithmic equation in exponential form: Using the property of logarithms, logb(y)=c    y=bc\log_{b}(y) = c \implies y = b^c, x=24-x = 2^4

  4. Simplify the exponential expression: x=16-x = 16

  5. Solve for xx: x=16x = -16

xx-intercept:

The xx-intercept of the function is at: x=16x = -16

Domain Note:

The logarithmic function log2(x)\log_{2}(-x) is only defined for x<0x < 0, so the solution x=16x = -16 is valid within the domain of the function.


Would you like me to graph this function to verify the intercept visually or provide a step-by-step breakdown of logarithmic properties?

Related Questions:

  1. How do logarithmic transformations affect the graph of a function?
  2. Can this method be generalized for any base of logarithm?
  3. What are the domain and range of f(x)=log2(x)4f(x) = \log_{2}(-x) - 4?
  4. How do we solve logarithmic equations with different bases?
  5. What happens if we set f(x)=cf(x) = c for any c0c \neq 0?

Tip:

Always check the domain restrictions when solving logarithmic functions, as the arguments must be positive for real values.

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Math Problem Analysis

Mathematical Concepts

Logarithms
Exponential Equations
Domain of Functions

Formulas

Logarithmic to Exponential Conversion: log_b(y) = c implies y = b^c
Domain Restriction: log_b(y) is defined only for y > 0

Theorems

Properties of Logarithms
Exponential Functions

Suitable Grade Level

Grades 9-12