Math Problem Statement

Solve for the variable: log_3 x + log_3 (x+2) = 1

Solution

The equation in the image is:

log3x+log3(x+2)=1\log_3{x} + \log_3{(x+2)} = 1

Step-by-step solution:

  1. Apply the logarithm property: The sum of two logarithms with the same base can be rewritten as the logarithm of the product:

    log3(x)+log3(x+2)=log3[x(x+2)]\log_3(x) + \log_3(x+2) = \log_3[x(x+2)]

    This simplifies to:

    log3[x(x+2)]=1\log_3[x(x+2)] = 1

  2. Exponentiate both sides: Since log3\log_3 is the logarithm base 3, we can exponentiate both sides to remove the logarithm:

    3log3[x(x+2)]=313^{\log_3[x(x+2)]} = 3^1

    This simplifies to:

    x(x+2)=3x(x + 2) = 3

  3. Expand and simplify: Expand the left side:

    x2+2x=3x^2 + 2x = 3

    Subtract 3 from both sides to set the equation equal to 0:

    x2+2x3=0x^2 + 2x - 3 = 0

  4. Factor the quadratic: Factor the quadratic equation:

    (x+3)(x1)=0(x + 3)(x - 1) = 0

  5. Solve for xx: Set each factor equal to 0:

    x+3=0orx1=0x + 3 = 0 \quad \text{or} \quad x - 1 = 0

    Solving these gives:

    x=3orx=1x = -3 \quad \text{or} \quad x = 1

  6. Check for extraneous solutions: Logarithms are only defined for positive arguments, so we must check if these values of xx are valid in the original equation.

    • For x=1x = 1, both log31\log_3{1} and log3(1+2)\log_3{(1 + 2)} are defined.
    • For x=3x = -3, log3(3)\log_3{(-3)} is not defined because logarithms of negative numbers are undefined in the real number system.

    Therefore, the only valid solution is x=1x = 1.

Final Answer:

The solution is x=1x = 1, which matches the selected answer.


Do you have any questions or would you like further details on any step?

Here are 5 related questions for practice:

  1. How would the equation change if the logarithm base was 10 instead of 3?
  2. Solve the equation log5x+log5(x+4)=1\log_5{x} + \log_5{(x+4)} = 1.
  3. Can you solve log2x+log2(x+3)=2\log_2{x} + \log_2{(x+3)} = 2?
  4. What happens if we have log3(x2)+log3(x+5)=2\log_3{(x-2)} + \log_3{(x+5)} = 2?
  5. What are the properties of logarithms that help simplify log expressions?

Tip: Always check if your logarithmic solutions make the arguments inside the log functions positive to avoid extraneous solutions.

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Math Problem Analysis

Mathematical Concepts

Logarithms
Algebra
Exponentiation
Quadratic Equations

Formulas

log_b (xy) = log_b (x) + log_b (y)
log_b (x) = y implies b^y = x
Quadratic equation formula: ax^2 + bx + c = 0

Theorems

Properties of Logarithms
Exponentiation Theorem

Suitable Grade Level

Grades 9-12