Example 2
Completion requirements
Example 2 |
Simplify \(\sqrt[{3}]{48}\).
Method 1: Prime factorization
Step 1: Rewrite the radicand as a product of prime factors.
\(\sqrt[3]{{48}} = \sqrt[3]{{2 \cdot 2\cdot 2\cdot 2\cdot 3}}\)
Step 2: Group as many identical factors as match the value of the index. Because the index is \(3\), group three factors of two, \(2 \cdot 2 \cdot 2\), and rewrite them as \(2^3\), a perfect cube.
\(\sqrt[3]{{{\color{red}2 \cdot 2\cdot 2}\cdot 2\cdot 3}} = \sqrt[3]{{2^3 \cdot 2\cdot 3}}\)
Step 3: Rewrite the radical as a product of the perfect cube radical and the non-perfect cube radicals.
\(\sqrt[3]{{2^3 \cdot 2 \cdot 3}} = \sqrt[3]{{2^3}} \cdot \sqrt[3]{{2\cdot 3}}\)
Step 4: Simplify.
\(\sqrt[3]{{2^3}}\cdot \sqrt[3]{{2\cdot 3}} = 2 \cdot \sqrt[3]{6}\)
Therefore, \(\sqrt[{3}]{48} = 2\sqrt[{3}]{6}\).
Method 2: Perfect cubes (because the index is 3)
Step 1: Rewrite the radicand as a product of factors, looking specifically for factors that are perfect cubes.
\(\begin{align}
\sqrt[3]{{48}} &= \sqrt[3]{{8\cdot 6}} \\
&= \sqrt[3]{{2^3 \cdot 6}} \\
\end{align}\)
Step 2: Rewrite the radical as a product of the perfect cube radical and the non-perfect cube radicals.
\(\sqrt[3]{{2^3 \cdot 6}} = \sqrt[3]{{2^3}} \cdot \sqrt[3]{6}\)
Step 3: Simplify.
\(\sqrt[3]{{2^3}}\cdot \sqrt[3]{6} = 2\sqrt[3]{6}\)
Therefore, \(\sqrt[3]{{48}} = 2\sqrt[3]{6}\).
Step 1: Rewrite the radicand as a product of prime factors.
\(\sqrt[3]{{48}} = \sqrt[3]{{2 \cdot 2\cdot 2\cdot 2\cdot 3}}\)
Step 2: Group as many identical factors as match the value of the index. Because the index is \(3\), group three factors of two, \(2 \cdot 2 \cdot 2\), and rewrite them as \(2^3\), a perfect cube.
\(\sqrt[3]{{{\color{red}2 \cdot 2\cdot 2}\cdot 2\cdot 3}} = \sqrt[3]{{2^3 \cdot 2\cdot 3}}\)
Step 3: Rewrite the radical as a product of the perfect cube radical and the non-perfect cube radicals.
\(\sqrt[3]{{2^3 \cdot 2 \cdot 3}} = \sqrt[3]{{2^3}} \cdot \sqrt[3]{{2\cdot 3}}\)
Step 4: Simplify.
\(\sqrt[3]{{2^3}}\cdot \sqrt[3]{{2\cdot 3}} = 2 \cdot \sqrt[3]{6}\)
Therefore, \(\sqrt[{3}]{48} = 2\sqrt[{3}]{6}\).
Method 2: Perfect cubes (because the index is 3)
Step 1: Rewrite the radicand as a product of factors, looking specifically for factors that are perfect cubes.
\(\begin{align}
\sqrt[3]{{48}} &= \sqrt[3]{{8\cdot 6}} \\
&= \sqrt[3]{{2^3 \cdot 6}} \\
\end{align}\)
Step 2: Rewrite the radical as a product of the perfect cube radical and the non-perfect cube radicals.
\(\sqrt[3]{{2^3 \cdot 6}} = \sqrt[3]{{2^3}} \cdot \sqrt[3]{6}\)
Step 3: Simplify.
\(\sqrt[3]{{2^3}}\cdot \sqrt[3]{6} = 2\sqrt[3]{6}\)
Therefore, \(\sqrt[3]{{48}} = 2\sqrt[3]{6}\).