Rewrite the irrational cube root 189−−−√3 as the product of an integer and another irrational cube root. Show your work.

1 answer

To rewrite the expression \( \sqrt[3]{189} \) as the product of an integer and another irrational cube root, we need to factor 189 into its prime factors and find perfect cube factors.

  1. Finding the prime factorization of 189: \[ 189 \div 3 = 63 \ 63 \div 3 = 21 \ 21 \div 3 = 7 \] So, the prime factorization of 189 is: \[ 189 = 3^3 \times 7 \]

  2. Identifying the perfect cube factor: The perfect cube in the factorization is \( 3^3 \).

  3. Rewriting the cube root: We can rewrite \( \sqrt[3]{189} \) as: \[ \sqrt[3]{189} = \sqrt[3]{3^3 \times 7} \] Using the property of cube roots, this can be separated into: \[ \sqrt[3]{189} = \sqrt[3]{3^3} \times \sqrt[3]{7} \]

  4. Calculating the cube root of the perfect cube: \[ \sqrt[3]{3^3} = 3 \]

  5. Combining the results: Therefore, we have: \[ \sqrt[3]{189} = 3 \times \sqrt[3]{7} \]

Thus, the expression \( \sqrt[3]{189} \) can be rewritten as the product of an integer and another irrational cube root: \[ \sqrt[3]{189} = 3 \sqrt[3]{7} \]