Prove by induction:
Use the Euclidean algorithm to determine the g.c.d. of 432
and 831. Then reverse the calculations to write the g.c.d. as a linear
combination of the two.
Show that the equation 3x2 - y3 = 176 has no solutions
with x and y integers, by considering the equation in \Bbb Z9.
Show that if n is odd, then the g.c.d. of n and n+8 is
always 1. (Hint: show that any k > 1 that divides n
can't divide
n+8.)
Show that a2 º 16(mod 10) implies a2 º 16(mod 20).
(Hint: show that 10|(a-4)(a+4) implies 5 divides one of the factors and 2 divides both of them ( a-4 is even if and only if a+4 is even!).)
Use the Euclidean algorithm to find
d = (217,133) and find integers x, y such that d = 217x + 133y.
Find the least non-negative residue of 3116
(mod 29).
Let p be a prime integer and suppose for some
a Î \Bbb Zp that a2 = a. Prove that a = [0]p or
a = [1]p in \Bbb Zp. Also, give an example to show that
this can be false if p is not a prime.
Prove by mathematical induction that 3 is a
divisor of 22n + 1 + 1 for every positive integer n.
Prove that [Ö15] is irrational.
Find the smallest positive integer in the set
{10u + 15v : u,v Î \Bbb Z}.
Write a sentence or two justifying your answer.
Prove that if a,b and c are integers such that
a|b and a|(b + c) then a|c.
What is the remainder when one divides (127)(244)(14)(-45)
by 13? (You don't need to actually perform long division.)
If p is a positive prime number and p|a2,
prove that p|a. (Be sure to state completely any
definition or theorem you use.)
Prove: If [a] = [1] in \Bbb Zn, then (a,n) = 1.