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If n is a positive integer such that \((^7\sqrt{10})(^7\sqrt{10})^2).....(^7\sqrt{10})^n) > 999\), then the smallest value of n is

Updated On: Jan 15, 2026
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Solution and Explanation

Given:
\((\sqrt[7]{10})(\sqrt[7]{10})^2 \cdots (\sqrt[7]{10})^n) > 999\)

This is equivalent to:
\(10^{\frac{1}{7}} \times 10^{\frac{2}{7}} \times \cdots \times 10^{\frac{n}{7}} > 999\)

Using the property of exponents (multiplying powers with the same base), we add the exponents:
\(10^{\left(\frac{1}{7} + \frac{2}{7} + \cdots + \frac{n}{7}\right)} > 999\)

This simplifies to:
\(10^{\left(\frac{1+2+\cdots+n}{7}\right)} > 999\)

We know that \(10^3 = 1000\), which is the closest power of 10 to 999. Therefore, we can write:
\(10^{\left(\frac{1+2+\cdots+n}{7}\right)} > 10^3\)

To find the minimum value of \(n\), we set the exponents equal:
\(\frac{1+2+\cdots+n}{7} = 3\)

This implies:
\(1+2+\cdots+n = 21\)

Calculating the sum for \(n = 6\):
\(1+2+3+4+5+6 = 21\)

Thus, the smallest possible value for \(n\) is 6.

Answer: The smallest value of \(n\) is 6.

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