Question

(y+3)^(2/3)-2(y+3)^(1/3)-3=0

Answer 1

Let (y+3)^1/3 = a

a^2 -2a -3 =0
(a-3)(a+1) =0
a =3, a = -1
(y+3)^1/3 = 3 or (y+3)^1/3 = -1
Take cubes on both side
y+3 = 27 or y +3 = -1
y = 24 or y = -4

Answer 2

y =24