That which is under the root sign is the same as (−3)2=9 and because
9=33=32, hence
(−3)2=9=912=3212=3221=31=3.
Note:
The calculation (−3)2=(−3)212=(−3)221=(−3)1=−3 is wrong at the second equals sign. Remember that the power rules apply when the base is positive.
3=32
(−3)2=
9=91
2=
32
1
21=31=3 