Math Problem Statement

Solve: \( \left(3^{\frac{x}{2}}\right) \times \left(3^{\frac{3x}{2}}\right) = 3^9 \) and \( 9^{x-4} = 3^{x-6} \)

Solution

Let’s carefully solve the two problems shown in the new image step by step:


Problem 1: Solve (3x2)×(33x2)=39\left(3^{\frac{x}{2}}\right) \times \left(3^{\frac{3x}{2}}\right) = 3^9


Step 1: Use the rule of exponents

The rule of exponents states: aman=am+na^m \cdot a^n = a^{m+n} Here, the base is 33. Combine the exponents: 3x233x2=3x2+3x23^{\frac{x}{2}} \cdot 3^{\frac{3x}{2}} = 3^{\frac{x}{2} + \frac{3x}{2}}

Add the exponents: x2+3x2=4x2=2x\frac{x}{2} + \frac{3x}{2} = \frac{4x}{2} = 2x

The left-hand side becomes: 32x3^{2x}

The equation now looks like: 32x=393^{2x} = 3^9


Step 2: Set the exponents equal to each other

Since the bases are the same, equate the exponents: 2x=92x = 9


Step 3: Solve for xx

x=92or 4.5x = \frac{9}{2} \quad \text{or } 4.5


Solution to Problem 1:

x=92or 4.5x = \frac{9}{2} \quad \text{or } 4.5


Problem 2: Solve 9x4=3x69^{x-4} = 3^{x-6}


Step 1: Rewrite the base 9 as 323^2

The base 99 can be rewritten as 323^2: 9x4=(32)x4=32(x4)=32x89^{x-4} = \left(3^2\right)^{x-4} = 3^{2(x-4)} = 3^{2x - 8}

The equation now becomes: 32x8=3x63^{2x - 8} = 3^{x-6}


Step 2: Set the exponents equal to each other

Since the bases are the same, equate the exponents: 2x8=x62x - 8 = x - 6


Step 3: Solve for xx

Simplify: 2xx=6+82x - x = -6 + 8 x=2x = 2


Solution to Problem 2:

x=2x = 2


Final Answers:

  1. For (3x2)×(33x2)=39\left(3^{\frac{x}{2}}\right) \times \left(3^{\frac{3x}{2}}\right) = 3^9, the solution is: x=92or 4.5x = \frac{9}{2} \quad \text{or } 4.5

  2. For 9x4=3x69^{x-4} = 3^{x-6}, the solution is: x=2x = 2

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Math Problem Analysis

Mathematical Concepts

Exponents and Powers
Algebra

Formulas

a^m \cdot a^n = a^{m+n}
Base conversion for powers (9 = 3^2)

Theorems

Properties of Exponents

Suitable Grade Level

Grades 8-10