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Question

If $(\frac{5}{3})^{x-3} = \frac{3125}{243}$, find the value of $(\frac{5}{3})^{\frac{x}{2}}$.

The correct answer is
$\frac{625}{81}$

Solving Exponential Equation

We are given the equation $(\frac{5}{3})^{x-3} = \frac{3125}{243}$ and asked to find the value of $(\frac{5}{3})^{\frac{x}{2}}$.

Simplifying Fraction Power

First, let's express the number $\frac{3125}{243}$ as a power of the base $\frac{5}{3}$.

We find the prime factors of the numerator and the denominator:

  • Numerator: $3125 = 5 \times 5 \times 5 \times 5 \times 5 = 5^5$
  • Denominator: $243 = 3 \times 3 \times 3 \times 3 \times 3 = 3^5$

Therefore, we can write $\frac{3125}{243}$ as:

$ \frac{3125}{243} = \frac{5^5}{3^5} = \left(\frac{5}{3}\right)^5 $

Our original equation now becomes:

$ \left(\frac{5}{3}\right)^{x-3} = \left(\frac{5}{3}\right)^5 $

Equating Exponents

Since the bases on both sides of the equation are the same ($\frac{5}{3}$), the exponents must be equal.

So, we set the exponents equal to each other:

$ x - 3 = 5 $

Solving for x

To find the value of $x$, we add 3 to both sides of the equation:

$ x = 5 + 3 $ $ x = 8 $

Now we know that $x = 8$.

Calculating Final Value

The question asks for the value of $(\frac{5}{3})^{\frac{x}{2}}$. We substitute the value of $x$ we found:

$ \left(\frac{5}{3}\right)^{\frac{x}{2}} = \left(\frac{5}{3}\right)^{\frac{8}{2}} $

Simplify the exponent:

$ \left(\frac{5}{3}\right)^{\frac{8}{2}} = \left(\frac{5}{3}\right)^4 $

Now, we calculate the value of $(\frac{5}{3})^4$:

$ \left(\frac{5}{3}\right)^4 = \frac{5^4}{3^4} $
  • $5^4 = 5 \times 5 \times 5 \times 5 = 625$
  • $3^4 = 3 \times 3 \times 3 \times 3 = 81$

So, the value is:

$ \frac{625}{81} $

Conclusion

The value of $(\frac{5}{3})^{\frac{x}{2}}$ is $\frac{625}{81}$.

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Important Questions from Algebra (Notes)

  1. If $(y-12) = 4\sqrt{5}$, then find the value of $\sqrt{y-3} - \frac{1}{\sqrt{y-3}}$.
  2. If $x^2 + \frac{1}{x^2} = 16$ and $x \neq 0$, then what is the value of $x^4 + \frac{1}{x^4}$?
  3. In the expansion of (x + 9)(x - 6)(x + 5), what is the coefficient of x?
  4. Find the value of $\frac{x+3}{x^2-2x} \times \frac{2x-1}{x^2+2x+4} \times \frac{x^4-8x}{2x^2+5x-3}$
  5. The roots of the equation $ax^3-24x^2+188x-480=0$ are three consecutive even natural numbers. The value of a is _____.
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