This is a fairly challenging problem from BL Math Games.
“Find the volume of the solid obtained by rotating the region enclosed by y = x and y = x2 about the line y = x.”
See Slanted Volume of Revolution for solutions.
This is a Valentine’s Day puzzle from BL’s (Barry Leung) Math Games.
“Happy Valentine’s Day everyone, I hope you are having a euphoric moment, but if not, you can try this algebra puzzle about maximizing the expression LUV + LU + UV + LV given L + U + V = 12, where L, U, V are non-negative integers.”
See Maximizing Love for a solution.
A recent video by Angela Collier about compound interest reminded me of an effort I did years ago to derive the formulas for interest calculations, especially for installment payments on a loan like a mortgage. In the process I showed where Euler’s constant e can show up. I thought I would resurrect the material, even though I imagine modern texts now provide the information (I couldn’t easily locate it back then).
This is another challenging sum from the 2024 Math Calendar.
“Find x where x = et and
”
As before, recall that all the answers are integer days of the month.
See Yet Another Sum for a solution.
Here is another problem from BL’s Weekly Math Games.
“For every point P on y = 2x2, areas A and B are equal. Find the equation for curve C.”
See Mystery Curve Puzzle for a solution
A while ago James Tanton provided a series of puzzles:
Puzzle #1 At what value between 0 and 1 does a horizontal line at that height produce two regions of equal area as shown on the graph of y = x2?
Puzzle #2 A horizontal line is drawn between the lines y = 0 and y = 1, dividing the graph of y = x2 into two regions as shown. At what height should that line be drawn so that the sum of the areas of these two regions is minimal?
Puzzle #3 A horizontal line is drawn between the lines y = 0 and y = 1, dividing the graph of y = xn into two regions as shown (n > 0). At what height should that line be drawn so that the sum of the areas of these two regions is minimal? Does that height depend on the value of n?
Puzzle #4 What horizontal line drawn between y = 0 and y = 1 on the graph of y = 2√x – 1 minimizes the sum of the two shaded areas shown?
See Double Areas Puzzles for solutions.
Here is a fairly computationally challenging 1994 AIME problem .
“Find the positive integer n for which
⌊log2 1⌋ + ⌊log2 2⌋ + ⌊log2 3⌋ + … + ⌊log2 n⌋ = 1994.
where for real x, ⌊x⌋ is the greatest integer ≤ x.”
There is some fussy consideration of indices.
See the Special Log Sum for a solution.
Well, I discovered that the 2024 Math Calendar has some interesting problems, so I guess things will limp along for a while. This is a challenging but imaginative problem from the calendar.
_______________
As before, recall that all the answers are integer days of the month.
See the Amazing Root Problem for a solution.
This is yet another series offered by Presh Talwalkar.
“What is the value of the following sum?
____
Talwalkar gives hints for three possible approaches to the solution.
See Another Challenging Sum for solutions.
Here is another UKMT Senior Challenge problem for 2017.
“The diagram shows a square PQRS with edges of length 1, and four arcs, each of which is a quarter of a circle. Arc TRU has centre P; arc VPW has centre R; arc UV has centre S; and arc WT has centre Q.
What is the length of the perimeter of the shaded region?
A_6___B_(2√2 – 1)π___C_(√2 – 1/2)π ___D_2___E_(3√2 – 2)π”
See Elliptic Circles for a solution.
