If I fail MA 2321 (or MA 3521) and re-take it as MA 2320 (or MA3520), how will that affect my GPA?

The two course pairs you mention are equivalent courses.  If you retake the first course (half semester version) by taking the second course (full semester version) the first grade is replaced by the second grade in your GPA.

 

  1. MA 2321 Elementary Linear Algebra
  2. MA 2320 Elementary Linear Algebra

 

  1. MA 3521 Elem Differential Equations
  2. MA 3520 Elem Differential Equations