Solve the Logarithmic Inequality: log₁/₂(5) - log₁/₂(4) ≤ log₁/₂(x) - log₁/₂(3)

Question

x=? x=\text{?}

log125log124log12xlog123 \log_{\frac{1}{2}}5-\log_{\frac{1}{2}}4\le\log_{\frac{1}{2}}x-\log_{\frac{1}{2}}3

Video Solution

Solution Steps

00:00 Solve
00:05 We'll use the logarithmic subtraction formula, we'll get the log of the numerator
00:17 Let's equate the logarithms
00:27 Let's isolate X
00:37 This is the appropriate domain
00:42 Let's check the domain of definition and find the solution
00:45 And this is the solution to the question

Step-by-Step Solution

To solve the inequality involving logarithms with base 12\frac{1}{2}, we will perform the following steps:

  • Step 1: Apply the subtraction property of logarithms.
  • Step 2: Simplify and solve the inequality.

Let's go through the steps:

Step 1: Simplify both sides using the logarithm subtraction rule:

Left side: log125log124=log12(54)\log_{\frac{1}{2}}5 - \log_{\frac{1}{2}}4 = \log_{\frac{1}{2}}\left(\frac{5}{4}\right)

Right side: log12xlog123=log12(x3)\log_{\frac{1}{2}}x - \log_{\frac{1}{2}}3 = \log_{\frac{1}{2}}\left(\frac{x}{3}\right)

This gives us the inequality:

log12(54)log12(x3)\log_{\frac{1}{2}}\left(\frac{5}{4}\right) \le \log_{\frac{1}{2}}\left(\frac{x}{3}\right)

Step 2: Since 12\frac{1}{2} is less than 1, the inequality sign flips when we remove the logarithms.

This gives: 54x3\frac{5}{4} \ge \frac{x}{3}

Multiplying both sides by 3 to solve for xx:

354x3 \cdot \frac{5}{4} \ge x

154x\frac{15}{4} \ge x

Thus, x154x \le \frac{15}{4}, which simplifies to x3.75x \le 3.75.

Since we assumed x>0x > 0, the final solution is:

0<x3.750 < x \le 3.75

Answer

0 < x\le3.75


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