1. 2. Define f: ZZ and 9: ZZ by f(x)=3x+1 and g(x) = x². (a) Calculate (go f)(2). (b) Find an explicit formula for the function gof. Define f: R2 R2 by f(x, y) = (3x+y, 5x+2y). Give an explicit formula for f-1. Verify that it is the inverse of f. Do not include a derivation for f¹ unless it is for the verification.

Suppose that two toothpaste companies compete for customers in a fixed market in which each customer uses either Brand A or Brand B. Suppose also that a market analysis shows that the buying habits of the customers fit the following pattern in the quarters that were analyzed: each quarter (three-month period), 30% of A users will switch to B, while the rest stay with A. Moreover, 40% of B users will switch to A in a given quarter, while the remaining B users will stay with B. Finally assume that this pattern does not vary from quarter to quarter. (a) If A initially has all of the customers, what are the market shares 2 quarters later? (b) If A initially has all of the customers, what are the market shares 20 quarters later? (c) If B initially has all of the customers, what are the market shares 2 quarters later? (d) If B initially has all of the customers, what are the market shares 20 quarters later?

1. The regular representation of a finite group G is a pair (Vreg, Dreg). Vreg is a vector space and Dreg is a homomorphism. (a) What is the dimension of Vreg? (b) Describe a basis for Vreg and give a formula for Dreg. Hence explain why the homo- morphism property is satisfied by Dreg. (c) Prove that the character ✗reg (g) defined by tr Dreg (g) is zero if g is not the identity element of the group. (d) A finite group of order 60 has five irreducible representations R1, R2, R3, R4, R5. R₁ is the trivial representation. R2, R3, R4 have dimensions (3,3,4) respectively. What is the dimension of R5? Explain how your solution is related to the decomposition of the regular representation as a direct sum of irreducible representations (You can assume without proof the properties of this decomposition which have been explained in class and in the lecture notes). (e) A group element has characters in the irreducible representations R2, R3, R4 given as R3 R2 (g) = -1 X³ (g) = −1 ; XR4 (g) = 0…