How do you find the cube roots root3(729)3729?

1 Answer
Nov 29, 2016

root(3)729=93729=9

Explanation:

Let us first factorize 729729 in to rime factors. As sum of digits of 729729 is 1818, it is divisible by 99 i.e. we can divide it twice by 33. Therefore

729=3xx3xx81729=3×3×81

Again 8181 is 9^292, hence divisible bt 33 four times more. Hence,

729=3xx3xx3xx3xx3xx3xx3729=3×3×3×3×3×3×3

and root(3)729=root(3)(ul(3xx3xx3)xxul(3xx3xx3))

= 3xx3=9