Math Problem Statement

Solve the equation 4^x - 3^((x-1)/2) = 3^((x+1)/2) - 2^(2x-1)

Solution

To solve the equation:

4x3x12=3x+1222x14^x - 3^{\frac{x-1}{2}} = 3^{\frac{x+1}{2}} - 2^{2x-1}

Let's simplify and solve for xx step-by-step.

Step 1: Rewrite the Exponential Terms

Convert the bases into simpler forms:

  1. 4x=(22)x=22x4^x = (2^2)^x = 2^{2x}
  2. 3x123^{\frac{x-1}{2}} and 3x+123^{\frac{x+1}{2}} are already in simplest exponential forms.
  3. 22x1=22x22^{2x-1} = \frac{2^{2x}}{2}

Thus, the equation becomes:

22x3x12=3x+1222x2.2^{2x} - 3^{\frac{x-1}{2}} = 3^{\frac{x+1}{2}} - \frac{2^{2x}}{2}.

Step 2: Combine Like Terms

Let's get the terms involving 22x2^{2x} together:

22x+22x2=3x+12+3x12.2^{2x} + \frac{2^{2x}}{2} = 3^{\frac{x+1}{2}} + 3^{\frac{x-1}{2}}.

Factor the left-hand side:

22x(1+12)=3x+12+3x12.2^{2x} \left(1 + \frac{1}{2}\right) = 3^{\frac{x+1}{2}} + 3^{\frac{x-1}{2}}.

Simplify:

3222x=3x+12+3x12.\frac{3}{2} \cdot 2^{2x} = 3^{\frac{x+1}{2}} + 3^{\frac{x-1}{2}}.

Step 3: Introduce a New Variable

Set y=3x12y = 3^{\frac{x-1}{2}}, so that:

3x+12=3y.3^{\frac{x+1}{2}} = 3 \cdot y.

Substitute into the equation:

3222x=y+3y=4y.\frac{3}{2} \cdot 2^{2x} = y + 3y = 4y.

Thus:

3222x=4y.\frac{3}{2} \cdot 2^{2x} = 4y.

Step 4: Solve for yy and xx

Rearrange for yy:

y=3822x.y = \frac{3}{8} \cdot 2^{2x}.

Since y=3x12y = 3^{\frac{x-1}{2}}, equate and solve for xx:

3x12=3822x.3^{\frac{x-1}{2}} = \frac{3}{8} \cdot 2^{2x}.

Take the logarithm of both sides and solve for xx.

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Math Problem Analysis

Mathematical Concepts

Exponential Equations
Logarithms
Algebra

Formulas

a^x = (b^y)^x = b^(y*x)
2^(2x-1) = (2^2x)/2

Theorems

Properties of Exponents
Logarithmic Operations

Suitable Grade Level

Grades 10-12 or Pre-Calculus