What is the cube root of $$ 343$$?
$$343=7\times 7\times 7$$
$$\therefore 343={ \left( 7 \right) }^{ 3 }$$
Taking cube roots on both sides,
$$\therefore \sqrt [ 3 ]{ 343 } $$
$$\therefore \sqrt [ 3 ]{ 343 } =\sqrt [ 3 ]{ { \left( 7 \right) }^{ 3 } } $$
$$\therefore \sqrt [ 3 ]{ 343 } ={ \left( { \left( 7 \right) }^{ 3 } \right) }^{ \frac { 1 }{ 3 } }$$
$$\therefore \sqrt [ 3 ]{ 343 } ={ 7 }$$