Second order partial derivatives

[tinkus]

Homework Statement

if z= f(x) + yg(x), what can you say about zyy explain?

Homework Equations

The Attempt at a Solution

z= f(x,yy)
zyy = d/dy (dz/dy) d(partial derivative)

 

[lanedance]

z = f(x,yy) this not correct, i am not sure what it means

try taking the partial derivative and see what you get

remember for partials, the other variable is kept constant during the differentiation, in this case x

 

[maze]

Consider that d/dx (a(x,y) + b(x,y)) = d/dx a(x,y) + d/dx b(x,y).

Also recall that d/dx (a(x,y)*b(x,y)) = (d/dx a(x,y))*b(x,y) + a(x,y)*(d/dx b(x,y)).