Prove that there exists infinitely many numbers of the form an = n(n+1)/2 , for some positive integer n, such that every pair an, am (for n != m) are relatively prime. [Hint: Assume there exists a finite sequence an1 < an2 < an3 < . . . < anm, where nj are increasing positive integers. Show that using those numbers we can construct a new number that fulfills the requirements.]
We have to show there is two natural numbers
n and m , such that an and am these two sequences of numbers are relatively prime that is gcd ( an , am ) = 1
Prove that there exists infinitely many numbers of the form an = n(n+1)/2 , for some...
Exercise 3. [10 pts Let n 2 1 be an integer. Prove that there exists an integer k 2 1 and a sequence of positive integers al , a2, . . . , ak such that ai+1 2 + ai for all i-1, 2, . . . , k-1 and The numbers Fo 0, F1 1, F2 1, F3 2 etc. are the Fibonacci numbers
Problem 11. Prove via induction that every integer n 2 can be expressed as a product of prime mumbers. You may use without proof that if n 2 2 is no such that n ab. t prime, then there exists integers a, b2 2 Problem 11. Prove via induction that every integer n 2 can be expressed as a product of prime mumbers. You may use without proof that if n 2 2 is no such that n ab. t...
Problem (5), 10 points Let a0:a1, a2, be a sequence of positive integers for which ao-1, and a2n2an an+ for n 2 0. Prove that an and an+l are relatively prime for every non-negative integer n. 2n+an for n >0 Problem (5), 10 points Let a0:a1, a2, be a sequence of positive integers for which ao-1, and a2n2an an+ for n 2 0. Prove that an and an+l are relatively prime for every non-negative integer n. 2n+an for n >0
let G be a finite group, prove that for every a in G there exists a positive integer n such that an=e, the identity.
8. (a) Prove that if p and q are prime numbers then p2 + pq is not a perfect square. (b) Prove that, for every integer a and every prime p, if p | a then ged(a,pb) = god(a,b). Is the converse of this statement true? Explain why or why not. (c) Prove that, for every non-zero integer n, the sum of all (positive or negative) divisors of n is equal to zero. 9. Let a and b be integers...
For Exercises 1-15, prove or disprove the given statement. 1. The product of any three consecutive integers is even. 2. The sum of any three consecutive integers is even. 3. The product of an integer and its square is even. 4. The sum of an integer and its cube is even. 5. Any positive integer can be written as the sum of the squares of two integers. 6. For a positive integer 7. For every prime number n, n +...
1. (Integers: primes, divisibility, parity.) (a) Let n be a positive integer. Prove that two numbers na +3n+6 and n2 + 2n +7 cannot be prime at the same time. (b) Find 15261527863698656776712345678%5 without using a calculator. (c) Let a be an integer number. Suppose a%2 = 1. Find all possible values of (4a +1)%6. 2. (Integers: %, =) (a) Suppose a, b, n are integer numbers and n > 0. Prove that (a+b)%n = (a%n +B%n)%n. (b) Let a,...
8. Define (n) to be the number of positive integers less than n and n. That is, (n) = {x e Z; 1 < x< n and gcd(x, n) = 1}|. Notice that U (n) |= ¢(n). For example U( 10) = {1, 3,7, 9} and therefore (10)= 4. It is well known that (n) is multiplicative. That is, if m, n are (mn) (m)¢(n). In general, (p") p" -p Also it's well known that there are relatively prime, then...
Prove using mathematical induction that for every positive integer n, = 1/i(i+1) = n/n+1. 2) Suppose r is a real number other than 1. Prove using mathematical induction that for every nonnegative integer n, = 1-r^n+1/1-r. 3) Prove using mathematical induction that for every nonnegative integer n, 1 + i+i! = (n+1)!. 4) Prove using mathematical induction that for every integer n>4, n!>2^n. 5) Prove using mathematical induction that for every positive integer n, 7 + 5 + 3 +.......
10. A natural number n is called attainable if there exists non-negative integers a and b such that n - 5a + 8b. Otherwise, n is called unattainable. Construct an 9 x 6 matrix whose rows are indexed by the integers between 0 and 8 and whose columns are indexed by the integers between 0 and 5 whose (x, y)-th entry equals 5x + 8y for any 0 < r < 8 and (a) Mark down all the attainable numbers...