Question

If z=cos(x), find the second derivative with respect to x . i.e. d^{2}y/dx^{2}

Answer 1

do you mean:
\[\frac{d^2z}{dx^2}\]
(z instead of y)

Answer 2

No, this is the exact question:

If z=sin(x) and if y is a function of x, show that

d^{2}y/dx^{2}=cos^{2}xd^{y}/dz^{2}-sin(x)dy/dz

Answer 3

I first found dy/dx using the chain rule. dy/dx=dy/dz.dz/dx=cos(x)dy/dz

I proceeded to find the second derivate w.r.t x but it does not match that given.