Math Problem Statement

ln\left(\frac{2}{:-y+3}\right)=ln:y

Solution

We are given the equation:

ln(2y+3)=lny\ln\left(\frac{2}{-y + 3}\right) = \ln y

To solve for yy, we can take the following steps:

Step 1: Use the property of logarithms

Since the natural logarithm (ln\ln) function is one-to-one, we can set the arguments inside the logarithms equal to each other:

2y+3=y\frac{2}{-y + 3} = y

Step 2: Multiply both sides by y+3-y + 3 to eliminate the fraction:

2=y(y+3)2 = y(-y + 3)

Step 3: Expand the right-hand side:

2=y2+3y2 = -y^2 + 3y

Step 4: Rearrange the equation into standard quadratic form:

y23y+2=0y^2 - 3y + 2 = 0

Step 5: Factor the quadratic equation:

(y1)(y2)=0(y - 1)(y - 2) = 0

Step 6: Solve for yy:

y=1ory=2y = 1 \quad \text{or} \quad y = 2

Step 7: Check for extraneous solutions

We need to check if both values of yy satisfy the original equation. Since the natural logarithm is only defined for positive values, we discard any negative or zero results from the argument of lny\ln y.

  • For y=1y = 1: ln(21+3)=ln1\ln\left(\frac{2}{-1 + 3}\right) = \ln 1 which gives ln1=ln1\ln 1 = \ln 1, a true statement.

  • For y=2y = 2: ln(22+3)=ln2\ln\left(\frac{2}{-2 + 3}\right) = \ln 2 which gives ln2=ln2\ln 2 = \ln 2, a true statement.

Conclusion:

Both y=1y = 1 and y=2y = 2 are valid solutions.

Would you like a more detailed explanation, or do you have any questions?

Here are some related questions to explore:

  1. What happens if we have ln(ab)=lnx\ln\left(\frac{a}{b}\right) = \ln x in general?
  2. How do you solve equations with multiple logarithms on each side?
  3. What are the conditions for a logarithmic function to be defined?
  4. How would this equation change if the logarithm base were different?
  5. What if we introduce a constant outside the logarithms, like cln(2y+3)=lnyc \cdot \ln\left(\frac{2}{-y + 3}\right) = \ln y?

Tip: Always remember to check the domain of the logarithmic function when solving logarithmic equations, as logarithms are only defined for positive numbers.

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Math Problem Analysis

Mathematical Concepts

Logarithmic Equations
Algebra
Quadratic Equations

Formulas

ln(a) = ln(b) implies a = b
Quadratic equation: ax^2 + bx + c = 0

Theorems

Logarithm Property: ln(a) = ln(b) implies a = b
Quadratic Factorization Theorem

Suitable Grade Level

Grades 10-12