Math 221D (Fall 2026)

• Lectures: MW 8:30am-9:45am, Physics 259
• Discussion section: F 8:30am-9:45am, Physics 047
• Office hours
  • Danielle’s OH: Mon 10am-11am, Wed 10am-11am, Physics 274E
  • Alina’s OH: Thu 5pm-7pm, Gross Hall 351
  • Math helproom for 221: Mon 7pm-9pm in Classroom Building 136; Tue 7pm-9pm, Wed 7pm-9pm, Thu 7pm-9pm in Physics 274J
• Textbook: Linear Algebra: A Geometric Approach (2nd Ed.) by Theodore Shifrin and Malcolm Adams
• Email: danielle.wang@duke.edu
• Gradescope

Syllabus

See syllabus document.

Homework

Problem sets will be posted on Gradescope, and will usually be due on Thursdays.

Exam information

• Midterm 1: Friday, October 2
  • Sections 1.1-2.3
  • Review problems for Midterm 1
• Midterm 2: Friday, November 6
• Final: Sunday, December 13

Schedule

• Aug 24: 1.1
• Aug 26: 1.2, 1.3
• Aug 31: 1.3, 1.4 Matrices and (reduced) echelon form
• Sep 2: 1.4 Gaussian elimination, 1.5
• Sep 4: Quiz 1, solutions
• Sep 9: 1.5, 1.6.1
• Sep 11: Quiz 2, solutions
• Sep 14: 2.1, 2.2 Linear transformations
• Sep 16: 2.2.1 Matrix of a linear transformation, 2.3
• Sep 18: Quiz 3, solutions
• Sep 21: 2.3
• Sep 23: 2.4, 2.5
• Sep 25: Quiz 4
• Sep 28: 2.5, 3.1