7. Let n ∈ N with n > 1 and let P be the set of polynomials
with coefficients in R.
(a) We define a relation, T, on P as follows: Let f, g ∈ P. Then
we say f T g if f −g = c for some c ∈ R. Show that T is an
equivalence relation on P.
(b) Let R be the set of equivalence classes of P and let F : R →
P be...
Let S = {a, b, c, d} and P(S) its power set. Define the minus
binary operation by A − B = {x ∈ S | x ∈ A but x /∈ B}. Show that
(by counter-examples) this binary operation is not associative, and
it does not have identity
The question is correct.
Let X be an n-element set of positive integers each of whose
elements is at most (2n - 2)/n. Use the pigeonhole
principle to show that X has 2 distinct nonempty subsets A ≠ B with
the property that the sum of the elements in A is equal to the sum
of the elements in B.
Let X Geom(p). For positive integers n, k define
P(X = n + k | X > n) = P(X = n + k) / P(X > n) :
Show that P(X = n + k | X > n) = P(X = k) and then briefly
argue, in words, why this is true for geometric random
variables.
Let A be a diagonalizable n × n matrix and let P be an
invertible n × n matrix such that B = P−1AP is the diagonal form of
A. Prove that Ak = PBkP−1, where k is a positive integer. Use the
result above to find the indicated power of A. A = 6 0 −4 7 −1 −4 6
0 −4 , A5 A5 =
Let A be a diagonalizable n × n
matrix and let P be an invertible n × n
matrix such that
B = P−1AP
is the diagonal form of A. Prove that
Ak = PBkP−1,
where k is a positive integer.
Use the result above to find A5
A =
4
0
−4
5
−1
−4
6
0
−6
Let G be a group, and let a ∈ G be a fixed element. Define a
function Φ : G → G by Φ(x) = ax−1a−1.
Prove that Φ is an isomorphism is and only if the group G is
abelian.
1)Show that a subset of a countable set is also countable.
2) Let P(n) be the statement that 13 + 23 +· · ·+n3 =(n(n +
1)/2)2 for the positive integer n.
a) What is the statement P(1)?
b) Show that P(1) is true, completing the basis step of
the proof.
c) What is the inductive hypothesis?
d) What do you need to prove in the inductive step?
e) Complete the inductive step, identifying where you
use the inductive hypothesis....
Let p be a prime and d a divisor of p-1. show that the d th
powers form a subgroup of U(Z/pZ) of order (p-1)/d. Calculate this
subgroup for p=11, d=5; p=17,d=4 ;p=19,d=6