# Given that y=(k+x)cosx where k is a constant find d^2y\dx^2 +y and show that it's independent of k ?

##### 1 Answer

Feb 15, 2017

See below.

#### Explanation:

By the Product Rule:

Same again:

This is independent of k.

To understand why, consider the simpler:

In this case:

To look at it another way,