Math Problem Statement

Solve the equation 𝑙𝑜𝑔3(𝑥^2 − 4𝑥 + 4) = 1 + 𝑙𝑜𝑔3(𝑥 − 2).

Solution

We are given the equation:

log3(x24x+4)=1+log3(x2)\log_3(x^2 - 4x + 4) = 1 + \log_3(x - 2)

Step 1: Simplify the equation

We can rewrite the equation using the logarithmic properties.

The right-hand side is:

1+log3(x2)1 + \log_3(x - 2)

We can express 1 as log3(3)\log_3(3), so the right-hand side becomes:

log3(3)+log3(x2)\log_3(3) + \log_3(x - 2)

Using the logarithmic property logb(a)+logb(c)=logb(ac)\log_b(a) + \log_b(c) = \log_b(ac), the right-hand side simplifies to:

log3(3(x2))\log_3(3(x - 2))

Thus, the equation becomes:

log3(x24x+4)=log3(3(x2))\log_3(x^2 - 4x + 4) = \log_3(3(x - 2))

Step 2: Remove the logarithms

Since the logarithms on both sides have the same base (base 3), we can remove the log3\log_3 terms and set the arguments equal to each other:

x24x+4=3(x2)x^2 - 4x + 4 = 3(x - 2)

Step 3: Solve the quadratic equation

Now expand and simplify the equation:

x24x+4=3x6x^2 - 4x + 4 = 3x - 6

Bring all terms to one side:

x24x+43x+6=0x^2 - 4x + 4 - 3x + 6 = 0

Simplify:

x27x+10=0x^2 - 7x + 10 = 0

Step 4: Factor the quadratic equation

We factor the quadratic equation:

x27x+10=(x5)(x2)=0x^2 - 7x + 10 = (x - 5)(x - 2) = 0

Step 5: Solve for xx

From the factored equation, the solutions are:

x5=0orx2=0x - 5 = 0 \quad \text{or} \quad x - 2 = 0

Thus, x=5x = 5 or x=2x = 2.

Step 6: Check for extraneous solutions

We need to check whether any of the solutions make the argument of the logarithm negative or zero, as logarithms are undefined for such values.

  • For x=5x = 5:

    • log3(5245+4)=log3(9)\log_3(5^2 - 4 \cdot 5 + 4) = \log_3(9), which is defined.
    • log3(52)=log3(3)\log_3(5 - 2) = \log_3(3), which is defined.
  • For x=2x = 2:

    • log3(2242+4)=log3(0)\log_3(2^2 - 4 \cdot 2 + 4) = \log_3(0), which is undefined.

Thus, x=2x = 2 is an extraneous solution.

Final Answer:

The only valid solution is:

x=5x = 5

Would you like more details or clarifications on any part of the solution?

Here are 5 related questions to deepen your understanding:

  1. What are the properties of logarithms that were used in this problem?
  2. How can you solve logarithmic equations with different bases?
  3. How do you determine if a solution is extraneous in logarithmic equations?
  4. Can the quadratic formula be used to solve all quadratic equations?
  5. How do logarithmic and exponential functions relate to each other?

Tip: Always check for extraneous solutions when solving logarithmic equations, as they can arise when the argument of the logarithm becomes zero or negative.

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Math Problem Analysis

Mathematical Concepts

Logarithms
Quadratic Equations
Properties of Logarithms

Formulas

log_b(a) + log_b(c) = log_b(ac)
Quadratic equation: ax² + bx + c = 0

Theorems

Logarithmic Identity: log_b(a) = log_b(c) implies a = c
Quadratic Formula: x = (-b ± √(b² - 4ac)) / 2a

Suitable Grade Level

Grades 9-11