(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.