Math Problem Statement

Solve for x: 5 + log_2(-5x) = 9

Solution

To solve the equation 5+log2(5x)=95 + \log_2(-5x) = 9, let's follow these steps:


Step 1: Isolate the logarithmic term

log2(5x)=95\log_2(-5x) = 9 - 5 log2(5x)=4\log_2(-5x) = 4


Step 2: Rewrite the equation in exponential form

The logarithmic property logb(y)=x\log_b(y) = x implies bx=yb^x = y. Here, b=2b = 2, x=4x = 4, and y=5xy = -5x. 24=5x2^4 = -5x 16=5x16 = -5x


Step 3: Solve for xx

x=165x = -\frac{16}{5} x=3.2x = -3.2


Step 4: Verify the solution

The argument of the logarithm, 5x-5x, must be positive for log2(5x)\log_2(-5x) to be defined: 5x=5(3.2)=16>0-5x = -5(-3.2) = 16 > 0 The condition is satisfied, so x=3.2x = -3.2 is valid.


Final Answer:

x=3.2\boxed{x = -3.2}


Do you want me to elaborate on any step?

Here are 5 related questions to explore:

  1. How do you convert logarithmic equations into exponential form?
  2. What are the domain restrictions for logarithmic functions?
  3. Can you solve logb(y)=c\log_b(y) = c when yy is not positive?
  4. How do you verify solutions for logarithmic equations?
  5. What are some real-life applications of logarithmic equations?

Tip: Always check the domain of the logarithmic function to ensure solutions are valid.

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Math Problem Analysis

Mathematical Concepts

Logarithmic Functions
Exponential Equations
Algebra

Formulas

log_b(y) = x implies b^x = y
Domain of logarithmic functions: log_b(y) is defined if y > 0

Theorems

Properties of Logarithms
Exponential and Logarithmic Relationship

Suitable Grade Level

Grades 10-12