If y = ex + e–x, prove that 
.
Given y = ex + e–x
On differentiating y with respect to x, we get
We know
[using chain rule]
We have 
But, y = ex + e–x
Thus, 
71
If y = ex + e–x, prove that .
Given y = ex + e–x
On differentiating y with respect to x, we get
We know
[using chain rule]
We have
But, y = ex + e–x
Thus,