(x+1)^(2/3) + (x-4)(2/3)(x+1)^(-1/3)=(x+1)^(-1/3) . [ x+1 + (2/3)(x-4) ]=(x+1)^(-1/3) . [ (5/3)x-5/3]=5(x-1)/[ 3. (x+1)^(1/3) ]
