15th Swedish Mathematical Society Problems 1975

1.  A is the point (1, 0), L is the line y = kx (where k > 0). For which points P (t, 0) can we find a point Q on L such that AQ and QP are perpendicular?2.  Is there a positive integer n such that the fractional part of (3 + √5)n > 0.99? 3.  Show that an + bn + cn ≥ abn-1 + bcn-1 + can-1 for real a, b, c ≥ 0 and n a positive integer. 4.  P1,

14th Swedish Mathematical Society Problems 1974

1.  Let an = 2n-1 for n > 0. Let bn = ∑r+s≤n aras. Find bn - bn-1, bn - 2bn-1 and bn.2.  Show that 1 - 1/k ≤ n(k1/n - 1) ≤ k - 1 for all positive integers n and positive reals k. 3.  Let a1 = 1, a2 = 2a1, a3 = 3a2, a4 = 4a3, ... , a9 = 9a8. Find the last two digits of a9. 4.  Find all polynomials p(x) such that p(x2) = p(x)

13th Swedish Mathematical Society Problems 1973

1.  log82 = 0.2525 in base 8 (to 4 places of decimals). Find log84 in base 8 (to 4 places of decimals). 2.  The Fibonacci sequence f1, f2, f3, ... is defined by f1 = f2 = 1, fn+2 = fn+1 + fn. Find all n such that fn = n2. 3.  ABC is a triangle with ∠A = 90o, ∠B = 60o. The points A1, B1, C1 on BC, CA, AB respectively are such that

12th Swedish Mathematical Society Problems 1972

1.  Find the largest real number a such that x - 4y = 1, ax + 3y = 1 has an integer solution. 2.  A rectangular grid of streets has m north-south streets and n east-west streets. For which m, n > 1 is it possible to start at an intersection and drive through each of the other intersections just once before returning to the start? 3.  A steak

11th Swedish Mathematical Society Problems 1971

1.  Show that (1 + a + a2)2 < 3(1 + a2 + a4) for real a ≠ 1. 2.  An arbitrary number of lines divide the plane into regions. Show that the regions can be colored red and blue so that neighboring regions have different colors. 3.  A table is covered by 15 pieces of paper. Show that we can remove 7 pieces so that the remaining 8 cover at least 8/15 of

10th Swedish Mathematical Society Problems 1970

1.  Show that infinitely many positive integers cannot be written as a sum of three fourth powers of integers. 2.  6 open disks in the plane are such that the center of no disk lies inside another. Show that no point lies inside all 6 disks.3.  A polynomial with integer coefficients takes the value 5 at five distinct integers. Show that it does not take the value 9

9th Swedish Mathematical Society Problems 1969

1.  Find all integers m, n such that m3 = n3 + n. 2.  Show that tan π/3n is irrational for all positive integers n. 3.  a1 ≥ a2 ≥ ... ≥ an is a sequence of reals. b1, b2, b3, ... bn is any rearrangement of the sequence B1 ≥ B2 ≥ ... ≥ Bn. Show that ∑ aibi ≤ &sum aiBi. 4.  Define g(x) as the largest value of |y2 - xy| for

8th Swedish Mathematical Society Problems 1968

1.  Find the maximum and minimum values of x2 + 2y2 + 3z2 for real x, y, z satisfying x2 + y2 + z2 = 1. 2.  How many different ways (up to rotation) are there of labeling the faces of a cube with the numbers 1, 2, ... , 6? 3.  Show that the sum of the squares of the sides of a quadrilateral is at least the sum of the squares of the diagonals. When

7th Swedish Mathematical Society Problems 1967

1.  p parallel lines are drawn in the plane and q lines perpendicular to them are also drawn. How many rectangles are bounded by the lines? 2.  You are given a ruler with two parallel straight edges a distance d apart. It may be used (1) to draw the line through two points, (2) given two points a distance ≥ d apart, to draw two parallel lines, one

6th Swedish Mathematical Society Problems 1966

1.  Let {x} denote the fractional part of x = x - [x]. The sequences x1, x2, x3, ... and y1, y2, y3, ... are such that lim {xn} = lim {yn} = 0. Is it true that lim {xn + yn} = 0? lim {xn - yn} = 0? 2.  a1 + a2 + ... + an = 0, for some k we have aj ≤ 0 for j ≤ k and aj ≥ 0 for j > k. If ai are not all 0, show that a1 + 2a2 + 3a3 + ..

5th Swedish Mathematical Society Problems 1965

1.  The feet of the altitudes in the triangle ABC are A', B', C'. Find the angles of A'B'C' in terms of the angles A, B, C. Show that the largest angle in A'B'C' is at least as big as the largest angle in ABC. When is it equal? 2.  Find all positive integers m, n such that m3 - n3 = 999. 3.  Show that for every real x ≥ ½ there is an integer n such

4th Swedish Mathematical Society Problems 1964

1.  Find the side lengths of the triangle ABC with area S and ∠BAC = x such that the side BC is as short as possible. 2.  Find all positive integers m, n such that n + (n+1) + (n+2) + ... + (n+m) = 1000. 3.  Find a polynomial with integer coefficients which has √2 + √3 and √2 + 31/3 as roots. 4.  Points H1, H2, ... , Hn are arranged in the

3rd Swedish Mathematical Society Problems 1963

1.  How many positive integers have square less than 107? 2.  The squares of a chessboard have side 4. What is the circumference of the largest circle that can be drawn entirely on the black squares of the board? 3.  What is the remainder on dividing 1234567 + 891011 by 12?