This page might be updated as the course progresses, including both review materials and lectures and sources to help with new material.
Here are some handouts:
 A trig circle, with all of the values of sine and cosine which we expect you to know.
 Sara's handout on series convergence, with crazy awesome colors
 Sara's handout on power series, also with crazy awesome colors
 A blank copy of Exam 1, blue version and the solutions to Exam 1, blue version
A blank copy of Exam 1, green version and the solutions to Exam 1, green version
 An introduction to differential equations, from
Boyce and DiPrima's book Elementary Differential Equations and Boundary Value Problems, sixth edition
 Sara's handout on Week 5 material, with all of the crazy awesome colors we love
 A section on firstorder linear differential equations
 A blank copy of Exam 2, blue version and the solutions to Exam 2, blue version
A blank copy of Exam 2, green version and the solutions to Exam 2, green version
 A section on series solutions for linear differential equations
 A handout on indexing and reindexing
 Sara's handout on the Week 8 material, which is the last time we will have those awesome colors. Please note that there is a slight omission in the Theorem, the equation must be homogenous for the theorem to be true.
Your first resource for help in the class should be the instructors and teaching assistants. You are welcome to office hours for any kind of question, we are here to help you and ready to explain the same thing as many times as necessary. You can also email us if you have any concerns, or if you would like to make an appointment to speak to one of us in private.
Stanford offers free drop in tutoring for Math 21 through the Center for Teaching and Learning (CTL). All of the information about this is on the Undergraduate tutoring website.
Some graduate students also offer their services to tutor for Math 21, you can find their names and email address on the list of private tutors maintained by the math department. Beware, private tutors tend to be expensive.
The following exams were given in previous incarnations of Math 21. The most relevant exams are the ones from Spring 2013. Before Spring 2013, the course material was arranged differently, with only one midterm and a final exam that was not cumulative. We will have a cumulative final exam this quarter. We have arranged the exams from before Spring 2013 according to the exam of ours that it resembles the most.
We will not provide solutions other than the ones already available here, but you are welcome to ask any instructor or course assistant to show you correct solutions to any problem.
Midterm 1

Midterm 2

Final Exam

Another interesting resource for this class is Khan Academy, a website which hosts short, very helpful lectures. Here are some particularly relevant videos, on a variety of topics that might come up this quarter.

Graphing:

Sigma notation:

Taylor polynomials
Here are some links and videos and things having to do with class:
