Applying the Negative Exponent

Oct 13, 2025 by windailys.com 98 views

Understanding the Problem

The given expression involves a negative exponent and a cube root. To evaluate this expression, we need to simplify the cube root and then apply the properties of exponents.

Simplifying the Cube Root

The cube root of 8 can be simplified as follows:

\sqrt[3]{8} = \sqrt[3]{2^3} = 2

Applying the Negative Exponent

Now that we have simplified the cube root, we can apply the negative exponent:

3^{-\sqrt[3]{8}} = 3^{-2}

Evaluating the Negative Exponent

To evaluate the negative exponent, we can use the property that $a^{-n} = \frac{1}{a^n}$ :

3^{-2} = \frac{1}{3^2} = \frac{1}{9}

Conclusion

Therefore, the value of the expression $$3^{-\sqrt[3]{8}}$$ is $\frac{1}{9}$ .

Comparison with the Given Options

Comparing the result with the given options, we can see that the correct answer is:

D. $\frac{1}{9}$

The other options are incorrect:

A. $-\frac{1}{9}$ : This is the negative of the correct answer, but the negative sign is not present in the original expression.
B. 91: This is a large number that is not related to the expression.
C. -9: This is a negative number that is not related to the expression.

Final Answer

The final answer is $\boxed{\frac{1}{9}}$ .

Understanding the Problem

The given expression involves a negative exponent and a cube root. To evaluate this expression, we need to simplify the cube root and then apply the properties of exponents.

Q&A: Evaluating the Expression

Q: What is the value of the cube root of 8?

A: The cube root of 8 can be simplified as follows:

\sqrt[3]{8} = \sqrt[3]{2^3} = 2

Q: How do I apply the negative exponent?

A: To apply the negative exponent, we can use the property that $a^{-n} = \frac{1}{a^n}$ :

3^{-2} = \frac{1}{3^2} = \frac{1}{9}

Q: What is the value of the expression $$3^{-\sqrt[3]{8}}$$?

A: The value of the expression $$3^{-\sqrt[3]{8}}$$ is $\frac{1}{9}$ .

Q: Why is the answer $\frac{1}{9}$ and not $-\frac{1}{9}$ ?

A: The answer is $\frac{1}{9}$ because the negative exponent is applied to the base 3, not the result of the cube root. The cube root of 8 is 2, and the negative exponent is applied to 3, resulting in $\frac{1}{9}$ .

Q: What are the other options, and why are they incorrect?

A: The other options are:

A. $-\frac{1}{9}$ : This is the negative of the correct answer, but the negative sign is not present in the original expression.
B. 91: This is a large number that is not related to the expression.
C. -9: This is a negative number that is not related to the expression.

These options are incorrect because they do not follow the rules of exponents and do not simplify the expression correctly.

Common Mistakes

Mistake 1: Not Simplifying the Cube Root

Error: Not simplifying the cube root of 8.
Correction: Simplify the cube root of 8 as $\sqrt[3]{2^3} = 2$ .

Mistake 2: Not Applying the Negative Exponent Correctly

Error: Applying the negative exponent to the result of the cube root instead of the base 3.
Correction: Apply the negative exponent to the base 3, resulting in $\frac{1}{9}$ .

Conclusion

Evaluating the expression $$3^{-\sqrt[3]{8}}$$ requires simplifying the cube root and applying the properties of exponents. By following the correct steps and avoiding common mistakes, we can arrive at the correct answer of $\frac{1}{9}$ .

Final Answer

The final answer is $\boxed{\frac{1}{9}}$ .