need help with differentiation question

For the following function, find y' and y"

x^(2/3) + y^(2/3) = a^(2/3) , 0<x<a , 0<y

how to solve this? I tried differentiating implicitly, but can't seem to understand how to differentiate the a^2/3 part.

a^2/3 is a constant..... so......?

but answer includes a ?

y'= -sqrt((a/x)^2/3 - 1)

y"= (a^2/3)/(3x^4/3 * sqrt(a^2/3 - x^2/3)

Answer is a constant, that means you have to sub in some values in part of the working.

That isn't the full question that you have posted I presume. Please refer to posting guidelines. Thanks.