Find The cube roots of the numbers 3048625, 20346417, 210644875, 57066625 using the fact that
Find The cube roots of the numbers 3048625, 20346417, 210644875, 57066625 using the fact that
(i) 3048625 = 3375 × 729
(ii) 20346417 = 9261 × 2197
(iii) 210644875 = 42875 × 4913
(iv) 57066625 = 166375 × 343
(i)
To find the cube root, we use the following property:
$\sqrt[3]{a b}=\sqrt[3]{a} \times \sqrt[3]{b}$ for two integers $a$ and $b$
now
$\sqrt[3]{3048625}$
$=\sqrt[3]{3375} \times 729$
$=\sqrt[3]{3375} \times \sqrt[3]{729}$ (By the above property)
$=\sqrt[3]{3 \times 3 \times 3 \times 5 \times 5 \times 5} \times \sqrt[3]{9 \times 9 \times 9} \quad$ (By prime factorisation)
$=\sqrt[3]{\{3 \times 3 \times 3\} \times\{5 \times 5 \times 5\}} \times \sqrt[3]{\{9 \times 9 \times 9\}}$
$=3 \times 5 \times 9$
$=3 \times 5 \times 9$
$=135$
Thus, the answer is 135.
(ii)
To find the cube root, we use the following property:
$\sqrt[3]{a b}=\sqrt[3]{a} \times \sqrt[3]{b}$ for two integers $a$ and $b$
Now,
$\sqrt[3]{20346417}$
$=\sqrt[3]{9261} \times 2197$
$=\sqrt[3]{9261} \times \sqrt[3]{2197}$ (By the above property)
$=\sqrt[3]{3 \times 3 \times 3 \times 7 \times 7 \times 7} \times \sqrt[3]{13 \times 13 \times 13}$ (By prime factorisation)
$=\sqrt[3]{\{3 \times 3 \times 3\} \times\{7 \times 7 \times 7\}} \times \sqrt[3]{\{13 \times 13 \times 13\}}$
$=3 \times 7 \times 13$
$=273$
Thus, the answer is 273.
(iii)
To find the cube root, we use the following property:
$\sqrt[3]{a b}=\sqrt[3]{a} \times \sqrt[3]{b}$ for two integers $a$ and $b$
Now
$\sqrt[3]{210644875}$
$=\sqrt[3]{42875} \times 4913$
$=\sqrt[3]{42875} \times \sqrt[3]{4913}$ (By the above property)
$=\sqrt[3]{5 \times 5 \times 5 \times 7 \times 7 \times 7} \times \sqrt[3]{17 \times 17 \times 17}$ (By prime factorisation)
$=\sqrt[3]{\{5 \times 5 \times 5\} \times\{7 \times 7 \times 7\}} \times \sqrt[3]{\{17 \times 17 \times 17\}}$
$=5 \times 7 \times 17$
$=595$
Thus, the answer is 595.
(iv)
To find the cube root, we use the following property:
$\sqrt[3]{a b}=\sqrt[3]{a} \times \sqrt[3]{b}$ for two integers $a$ and $b$
now
$\sqrt[3]{57066625}$
$=\sqrt[3]{166375} \times 343$
$=\sqrt[3]{166375} \times \sqrt[3]{343}$ (By the above property)
$=\sqrt[3]{5 \times 5 \times 5 \times 11 \times 11 \times 11} \times \sqrt[3]{7 \times 7 \times 7} \quad$ (By prime factorisation)
$=\sqrt[3]{\{5 \times 5 \times 5\} \times\{11 \times 11 \times 11\} \times \sqrt[3]{\{7 \times 7 \times 7\}}}$
$=5 \times 11 \times 7$
$=385$
Thus, the answer is 385.