Math Problem Statement

Solve the exponential equation. Express irrational solutions as decimals correct to the nearest thousandth.

2 Superscript x minus 2 Baseline equals 3 Superscript 2 x2x−2=32x

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Part 1

Select the correct choice below​ and, if​ necessary, fill in the answer box to complete your choice.

A.

The solution set is

StartSet nothing EndSetenter your response here.

​(Round to the nearest thousandth as needed. Use a comma to separate answers as​ needed.)

B.

The solution is the empty set.

Solution

To solve the exponential equation 2x2=32x2^{x-2} = 3^{2x}, we will proceed step-by-step.


Step 1: Rewrite the equation

2x2=32x2^{x-2} = 3^{2x}

Rewriting 2x22^{x-2} as 2x22=2x4\frac{2^x}{2^2} = \frac{2^x}{4}, the equation becomes: 2x4=32x\frac{2^x}{4} = 3^{2x}

Multiply through by 4 to eliminate the denominator: 2x=432x2^x = 4 \cdot 3^{2x}


Step 2: Take the natural logarithm of both sides

ln(2x)=ln(432x)\ln(2^x) = \ln(4 \cdot 3^{2x})

Using logarithmic properties: xln(2)=ln(4)+ln(32x)x \ln(2) = \ln(4) + \ln(3^{2x})

xln(2)=ln(4)+2xln(3)x \ln(2) = \ln(4) + 2x \ln(3)


Step 3: Rearrange to isolate xx

Group terms involving xx on one side: xln(2)2xln(3)=ln(4)x \ln(2) - 2x \ln(3) = \ln(4)

Factor out xx: x(ln(2)2ln(3))=ln(4)x (\ln(2) - 2\ln(3)) = \ln(4)

Solve for xx: x=ln(4)ln(2)2ln(3)x = \frac{\ln(4)}{\ln(2) - 2\ln(3)}


Step 4: Calculate the values

Using approximate values for logarithms:

  • ln(2)0.693\ln(2) \approx 0.693
  • ln(3)1.099\ln(3) \approx 1.099
  • ln(4)=2ln(2)1.386\ln(4) = 2 \cdot \ln(2) \approx 1.386

Substitute into the equation: x=1.3860.6932(1.099)x = \frac{1.386}{0.693 - 2(1.099)}

Simplify the denominator: x=1.3860.6932.198x = \frac{1.386}{0.693 - 2.198}

x=1.3861.505x = \frac{1.386}{-1.505}

x0.921x \approx -0.921


Final Answer:

The solution is: x0.921x \approx -0.921

Correct Choice: A. The solution set is {0.921}\{-0.921\}.


Do you want a deeper explanation or help with related problems? Here are 5 questions to expand your understanding:

  1. How do logarithmic properties simplify solving exponential equations?
  2. Why is taking the natural logarithm useful in this equation?
  3. Can the equation 2x2=32x2^{x-2} = 3^{2x} have more than one solution?
  4. How does the sign of the denominator affect the solution?
  5. Could this problem be solved graphically, and what would that look like?

Tip: Always simplify the exponential base before taking logarithms; it can make calculations easier!

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Math Problem Analysis

Mathematical Concepts

Exponential Equations
Logarithms
Properties of Logarithms

Formulas

Logarithmic property: ln(a^b) = b * ln(a)
Equation solving: x = ln(b)/ln(a)

Theorems

Laws of Logarithms
Change of Base Theorem for Logarithms

Suitable Grade Level

Grades 10-12