Math Problem Statement

Solve the equation 3^(2x) - 3^(x+1) = 10, giving the value of x.

Solution

The problem is to solve the equation:

32x3x+1=103^{2x} - 3^{x+1} = 10

Step-by-Step Solution:

Step 1: Rewrite 32x3^{2x} in terms of 3x3^x

We know that: 32x=(3x)23^{2x} = (3^x)^2

So the equation becomes: (3x)233x=10(3^x)^2 - 3 \cdot 3^x = 10

Step 2: Let y=3xy = 3^x

Substituting yy for 3x3^x, the equation becomes: y23y10=0y^2 - 3y - 10 = 0

Step 3: Solve the quadratic equation

The equation y23y10=0y^2 - 3y - 10 = 0 can be factored as: (y5)(y+2)=0(y - 5)(y + 2) = 0

Thus: y=5ory=2y = 5 \quad \text{or} \quad y = -2

Step 4: Back-substitute y=3xy = 3^x

Since 3x>03^x > 0, we reject y=2y = -2. Therefore: 3x=53^x = 5

Step 5: Solve for xx

Take the logarithm of both sides: xln(3)=ln(5)x \ln(3) = \ln(5)

Solve for xx: x=ln(5)ln(3)x = \frac{\ln(5)}{\ln(3)}

Final Answer:

x=ln(5)ln(3)1.46497x = \frac{\ln(5)}{\ln(3)} \approx 1.46497


Would you like a detailed explanation of any step?

Related Questions:

  1. What are logarithms, and how are they applied to solve exponential equations?
  2. Can you solve the same equation graphically?
  3. How does rejecting y=2y = -2 affect the solution in exponential equations?
  4. What is the general process of converting a quadratic exponential equation into a solvable form?
  5. Can this equation have complex solutions?

Tip: To solve exponential equations, substituting variables and working through logarithmic operations is often a clean and effective approach.

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Math Problem Analysis

Mathematical Concepts

Exponential Equations
Quadratic Equations
Logarithms

Formulas

y^2 - 3y - 10 = 0 (quadratic form)
logarithmic transformation x * ln(a) = ln(b)

Theorems

Logarithm properties
Quadratic factorization

Suitable Grade Level

Grades 9-12