the question asked for square root but he cubes root it so he is wrong
He cancelled the index notation when he was not supposed to.
He cube rooted the numbers
In line 1, you should not cross out the notations '3' because it can not be square rooted.
he cannot cross the powers as it is square rootnot cube
He cannot cross out powers.
You cannot cross out the index notation like this.
do not cross out powers BECAUSE they are POWERFUL