How do I differentiate this equation

y=√x(x-14)

I thought it is like this: x^1/2(1-0)=x^1/2 or √x, but it is not, so how do I do this problem?

and how to differentiate this:

S(R) = 7πR2 ?

thank you

y=x^(1/2)(x-14)=x^(3/2)-14x^(1/2) since x=x^1 so x^(1/2)Xx^1=x^(1/2 + 1)=x^(3/2)
and dy/dx=(3/2)x^(1/2) - 7x^(-1/2) or (3/2)√x - 7/√x

I think this is πR^2 and πis a constant giving
dS/dR=14πR since the differential of R^2 is 2R