- #1

sooty1892

- 5

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## Homework Statement

Differentiate twice: z = sinx

## Homework Equations

Product rule

Chain rule

## The Attempt at a Solution

dy/dx = dy/dz * dz/dx

dy/dx = dy/dz * cosx

Using the product rule:

d^2y/dx^2 = d^2y/dz^2 * cosx - dy/dz * sinx

According to the answer in the book the answer is: d^2y/dx^2 = d^2y/dz^2 * cos

**^2**x - dy/dz * sinx but I don't see how.

Thanks for any help.