Prove it with the definition of infinitesimal of the same order. That is to say, it is proved that the limit of the ratio of the two is a non-zero constant.

For example, the first property, α/α= 1, so the limit is 1. So they are infinitesimals of the same order.

For the remaining two properties, you set the limit of the ratio of the two to a non-zero constant k, and then use the limit algorithm to deduce and prove it.

Please adopt it, thank you!