2-1

I’m not sure what you mean by "2-1." Do you mean:

• 2 − 1 = 1 (a quick arithmetic check),
• a problem labeled "2-1" from a textbook (Chapter 2, Section 1), or
• a specific topic called “Section 2.1” in a course (e.g., calculus, linear algebra, etc.)?

Please paste the full problem or tell me the subject and course, and I’ll walk you through a step-by-step solution. If you want a quick start, I can also give a general approach for typical Section 2.1 problems in your course.