Find the Inverse

I got the first one but need help with the second!

Let me know if you would like to see my work~

Write the first as

y  =  ( n + 2)^(1/5)      take both sides to the 5th power

y^5  = n + 2       subtract 2 from both sides

y^5  - 2  = n         "swap" n  and y

n^5  - 2  =  y      for y, write  f^-1 (n)..so...

f^-1(n)  = n^5  - 2

Second one 

y  = -2x^3  - 1      add 1 to both sides

y  + 1  =  -2x^3       multiply through by - 1

- (y + 1)  = 2x^3       divide both sides by 2

-(y + 1) / 2  =  x^3        take the cube root of both sides

[ - (y + 1)  / 2 ] ^(1/3)  =  x      "swap "  x  and y

[ - ( x + 1) / 2 ]^(1/3)  =  y      for y, write  f^-1(x)

f^-1(x)  =  [ - (x + 1) / 2 ] ^(1/3)

Yes, instead of f(x), set it to y!