Problem

Simplify cube root of fifth root of 6

The problem asks to perform an operation involving two different types of roots on the number 6. Specifically, the operation involves first taking the fifth root of 6, which is the value that when raised to the power of 5 gives 6, and then taking the cube root of that result, which is the value that when raised to the power of 3 gives the fifth root of 6. The goal is to simplify this expression to find the simplest radical form or possibly a decimal approximation if necessary.

$\sqrt[3]{\sqrt[5]{6}}$

Answer

Expert–verified

Solution:

Step 1:

Express $\sqrt[3]{\sqrt[5]{6}}$ as a single radical by multiplying the indices, resulting in $\sqrt[15]{6}$.

Step 2:

This expression can be represented in various ways. In its exact form, it remains $\sqrt[15]{6}$. To express it as a decimal, it approximates to $1.12687761 \ldots$

Knowledge Notes:

To simplify nested radicals, such as a cube root of a fifth root, you can use the property of exponents that states $(a^{m})^{n} = a^{m \cdot n}$. In the context of radicals, this means that the cube root of the fifth root of a number is the same as the fifteenth root of that number, since $3 \times 5 = 15$.

The cube root of a number $a$ is written as $\sqrt[3]{a}$, and the fifth root of a number $b$ is written as $\sqrt[5]{b}$. If you have a cube root of a fifth root, you can combine them by multiplying the root indices (3 and 5) to get the fifteenth root of the number, which is written as $\sqrt[15]{a}$ if $a$ is the number inside the fifth root.

The exact form of a radical expression is the one that contains the radical sign and the number inside it, without any decimal or fractional approximation. In this case, the exact form is $\sqrt[15]{6}$.

The decimal form of a radical expression is a numerical approximation of the radical's value. Since most radicals do not result in a perfect integer or a simple fraction, a decimal approximation is often used for practical calculations. This approximation can be found using a calculator or a computer algebra system.

In summary, the key knowledge points involved in this solution are:

  • Properties of exponents and radicals
  • Simplifying nested radicals by multiplying indices
  • Representing radical expressions in exact and decimal forms
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