## MAE 301 Review for Midterm II

5.1.2 Understand the basis for the principle of mathematical induction. Be able to derive the formulas for the sum of the first n numbers and for the sum of the first n squares. Understand why the "proof" presented in Problem 12 p 5-16 (that any set of coins chosen from a box will have the same denomination) is not a correct induction proof. Be able to use induction to prove elementary properties of the Fibonacci sequence (Problem 3 p 5-21) and to prove the Binomial Theorem (Problem 12 p 5-21).

5.2.1 Be able to explain the connection between "long division" and the ``Division Algorithm'' (the long division algorithm is a schematic version of the proof of the Division Algorithm, which is, strictly speaking, misnamed).

5.2.2 Understand why the Euclidean Algorithm takes as input two positive integers a,b and gives their greatest common divisor (a,b) as output. Be able to use the Euclidean Algorithm to calculate greatest common divisors.

5.2.5 Understand the statement and be able to prove Theorem 5.16: For any integer b > 1 any positive integer has a unique representation in base b. Be able to implement the proof explicitly in switching back and forth between decimal (base 10) and binary (base 2) representations of given numbers.

5.3.1 Understand the parallelism between divisibility calculations with polynomials (with coefficients in a field F, for example the real numbers, the rational numbers, or the complex numbers) and those with integers. Be able to implement the ``Division Algorithm'' for such polynomials.

6.2 Be able to define ``equivalence relation'' and be able to prove that for any integer k, congruence mod k is an equivalence relation. Be able to calculate additive inverses and multiplicative inverses (when k is prime) mod k (Problems 5, 6 p 6-8).

7.1.4 Understand the definition of ``congruence transformation'' (p 7-33). We also call such a transformation an ``isometry.''

7.2.1 Be able to prove that a translation is an isometry. Be able to prove that the composition of two translations is a translation.

7.2.2 Be able to prove that a rotation is an isometry. Understand how rotations about the origin in R2 are represented by 2 x 2 matrices (p 7-46). Understand how writing the matrix product for the composition of two rotations about the origin leads to the addition formulas for sin and cos. Be able to express a rotation about a point P not the origin in terms of translations and a rotation about the origin. Be able to implement this calculation to give the x,y-coordinates of the image of a point (a,b) after rotation by 45o about the point P = (-1,2) for example.

7.2.3 Be able to prove that a reflection is an isometry. Be able to prove that the composition of two reflections is a rotation (when the lines of reflection meet) or a translation (when the lines are parallel). Be able to implement this calculation to give the x,y-coordinates of the image of a point (a,b) after reflection about the line x-y=3 and then reflection about the line y=2x for example.

7.4.1 Be able to give proofs of the SAS and ASA theorems in terms of congruences (as on p 7-92 and 7-94).

November 16 2001