for the first one..

y = x/ln(x)

alright, so, quotient rule states:

(u'v - v'u)/(v^2)

let u = x, and v = ln(x)

and keep in mind that the derivative of ln(x) = 1/x

give that a shot

for the second one,

square root (sin(x) + cos(x)) can be written as..

(sinx + cosx)^(1/2)

using the chain rule,

(1/2)[(sinx + cosx)^(-1/2)] (cos(x) - sin(x))

keeping in mind that the derivative of sinx = cosx, and the derivative of cosx = -sinx.

the third one I'm not really sure what you meant by it, so, try to clarify hehe