(1) converts the cube root x into t.
The square of x under the third root number is equal to (x under the third root number) to get the square of the whole.
t^2+3t-4=0
(t+4)(t- 1)=0
T=-4 or t= 1.
So x=-64 or x= 1.
Then change the x power of 3 to n.
n^2-2n-3=0
(n-3)(n+ 1)=0
N=3 or n=- 1
x= 1
This problem uses the substitution method and needs to be observed as a whole. Examine the flexibility of thinking.