22. On its own, is not invertible because it's not one-to-one because it's periodic. For instance, we can always find more than one value of for which ; this happens when .
But we can restrict the domain so that it can become invertible. If we only allow values of within , for example, then each will only be associated with a single value of . This is how the standard inverse sine is defined. With (restricted domain of sine), we guarantee that (range). So the domain of the inverse is , and the range of the inverse is .
is not in this restricted domain. But still exists as long as we take the standard domain (the entire real line), and . But then because this is the only value of for which .
In short: and are NOT inverses of one another, but rather one is an imperfect inverse of the other.
The first step when factoring any polynomial is to factor out the GCF. The GCF is the greatest common factor for all the terms of the polynomial. By factoring out the GCF first, the coefficients and constant term of the polynomial will be reduced.