Solve the Logarithmic Equation: (2log₃2 + log₃x)log₂3 - log₂x = 3x-7

Question

(2log32+log3x)log23log2x=3x7 (2\log_32+\log_3x)\log_23-\log_2x=3x-7

x=? x=\text{?}

Video Solution

Solution Steps

00:00 Find X
00:05 We'll use the power log formula, move the coefficient into the log
00:17 We'll use this formula in our exercise
00:37 We'll use the logical addition formula, we'll get the log of their product
00:42 We'll use this formula in our exercise
01:03 We'll use the logical multiplication formula, we'll switch between the numbers
01:18 We'll use this formula in our exercise
01:33 The log of any number in its own base is always equal to 1
01:38 We'll use this formula in our exercise
01:53 We'll use the logical subtraction formula, we'll get the log of their quotient
02:03 We'll use this formula in our exercise
02:18 Let's calculate the log and substitute
02:38 We'll isolate X and solve to find the solution
02:48 And this is the solution to the question

Step-by-Step Solution

Let's solve the given equation step by step:

We start with:

(2log32+log3x)log23log2x=3x7(2\log_3 2 + \log_3 x)\log_2 3 - \log_2 x = 3x - 7

Firstly, use the change of base formula to convert log23\log_2 3 to base 3:

log23=log33log32=1log32\log_2 3 = \frac{\log_3 3}{\log_3 2} = \frac{1}{\log_3 2}

Substitute this expression into the original equation:

(2log32+log3x)(1log32)log2x=3x7(2\log_3 2 + \log_3 x)\left(\frac{1}{\log_3 2}\right) - \log_2 x = 3x - 7

Simplify the first term:

2log32+log3xlog32=2+log3xlog32\frac{2\log_3 2 + \log_3 x}{\log_3 2} = 2 + \frac{\log_3 x}{\log_3 2}

Thus, the equation becomes:

2+log3xlog32log2x=3x72 + \frac{\log_3 x}{\log_3 2} - \log_2 x = 3x - 7

Convert log2x\log_2 x to base 3 using change of base:

log2x=log3xlog32\log_2 x = \frac{\log_3 x}{\log_3 2}

Substitute back into the equation:

2+log3xlog32log3xlog32=3x72 + \frac{\log_3 x}{\log_3 2} - \frac{\log_3 x}{\log_3 2} = 3x - 7

The middle terms cancel out, simplifying to:

2 = 3x - 7

Solving for xx:

Add 7 to both sides:

9=3x9 = 3x

Divide by 3:

x=3x = 3

Thus, the solution to the problem is x=3x = 3.

Answer

3 3


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