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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. A square matrix having all the elements above the leading diagonal equal to zero is known as:
  2. If $(\frac{7}{11})^{k-5} = (\frac{11}{7})^{k-9}$, find the value of $2^k$.
  3. The sum of the age of A and 5 times the age of B is 36 years. When 3 times the age of A is added to 7 times the age of B, the result is 62 years. The sum of the ages (in years) of A and B is:
  4. 18 bags and 3 pens together cost ₹1,164, whereas 14 bags and 2 pens together cost ₹922. The cost of 9 bags exceeds the cost of 2 pens by:
  5. The cost of 2 pens and 5 notebooks is ₹187. The cost of 8 notebooks exceeds the cost of 4 pens by 40. What is the cost of 8 pens and 7 notebooks?
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