Is it right to use a bare infinitive as a subject complement as in the following quote?
"Its true purpose is convince shoppers that your product is the preferred choice"
"Their purpose is convince holders of political office of the importance of their industry but also to inform them about their expert knowledge and responsibility in their respective industry."
I am aware of that bare infinitive can be used when the sentence contains do as in this example:
The thing to do is [call for a taxi].