A Mistake in Limit

Problem

Find

Please find the mistake in the following calculation:

What conceptual mistake can you find in the above calculation?

The Point

Hey! Dear friend. When we write x → ∞, we means x → +∞ or x → -∞.

When x → +∞, we can get the above result, that is,

But when x → -∞, we let :

Put y = -x. As x→ -∞, y → +∞.

Then

Haha! There are two different answers, one for x → +∞ and another for x → -∞

The following graph illustrates the way as x → +∞ and x → -∞ :