A blog for enthusiastic math-lovers!

AIME 2012 problem

#12 on this year’s AIME, could it possibly be a simple problem with a simple solution?

Let \triangle ABC be a right triangle with right angle at C. Let D and E be points on \overline{AB} with D between A and E such that \overline{CD} and \overline{CE} trisect \angle C. If \frac{DE}{BE} = \frac{8}{15}, then \tan B can be written as \frac{m \sqrt{p}}{n}, where m and n are relatively prime positive integers, and p is a positive integer not divisible by the square of any prime. Find m+n+p.

AMC 2012 problem

This month has been crazy! It’s almost February 29th, since 2012 is a leap year. About a month ago I attended SUMiT and had an amazing time. I met many people my age interested in math like me. It was organized very well, thanks to GirlAngle and others.

Also in the past month were the AMC’s. On the AMC12 A, there was one problem that particularly intrigued me problem 2: See if you find a nice solution

Consider the polynomial

P(x)=\prod_{k=0}^{10}(x^{2^k}+2^k)=(x+1)(x^2+2)(x^4+4)\cdots (x^{1024}+1024)

The coefficient of x^{2012} is equal to 2^a. What is a?

\textbf{(A)}\ 5\qquad\textbf{(B)}\ 6\qquad\textbf{(C)}\ 7\qquad\textbf{(D)}\ 10\qquad\textbf{(E)}\ 24

It’s 2012!

Happy new year everyone! It’s 2012=2^2*503! Let’s start the year off with a simple problem: A palindrome is a number that reads the same forwards and backwards. How many digits does the 2012th palindrome have?

Please keep working on the last couple problems. I posted the solution to the first problem. Please comment if you want a hint!

Telescoping problem

The following problem is also a telescoping problem which is found on the 2005 Purple Comet Competition, #20. Please comment if you have any ideas! Note that it uses similar techniques as some of the previous problems that I posted, so please work on them also!

The summation \sum_{k=1}^{360} \frac{1}{k\sqrt{k+1}+(k+1)\sqrt{k}} is the ratio of two relatively prime positive integers m and n . Find m+n .


Another Summation Problem

Please continue to work on the previous problem; I will post hints or solutions to that in the near future!

Regardless: A cool pattern of polynomials goes as follows-

(x+1)^2=x^2+2x+1

(x^2+x+1)^2=x^4+2x^3+3x^2+2x+1

(x^3+x^2+x+1)^2=x^6+2x^5+3x^4+4x^3+3x^2+2x+1

….

See if you can use this little tip to simplify the following problem (which comes from AIME 2003, number 15!). It combines this tip and the ideas emphasized in the previous post!

Let P(x) = 24x^{24}+\sum_{j = 1}^{23}(24-j)(x^{24-j}+x^{24+j}).

Let z_{1},z_{2},\ldots,z_{r} be the distinct zeros of P(x), and letz_{k}^{2}= a_{k}+b_{k}i fork = 1,2,\ldots,r, where i =\sqrt{-1}, and a_{k} and b_{k} are real numbers.

Let \sum_{k = 1}^{r}|b_{k}| = m+n\sqrt{p}, where n, m  and p are integers and p is not divisible by the square of any prime. Find n+m+p.

Note that this problem involves multiple steps; even if you don’t know the entire solution to it, feel free to comment with intermediate steps or ideas you may have.

Topic 1: Summations

When I was younger, I always believed that working with problems that looked short and that did not have many scary symbols was easier than dealing with long, complex looking questions. Concepts which especially intimidated me were summations and floor functions. Just by the look of them, they seem s like a mess. However, in reality there are problems in those topics that are very simple!

In summations, often times a concept called telescoping comes into play. Telescoping is when you are able to cancel out most terms in the summation. In summations it is also helpful to sometimes reorganize your problem.

Summations problems come in all different shapes and sizes. The following problem is #14 on the AIME which I spoke about in my previous post.

For each positive integer n, let f(n) =\sum_{k = 1}^{100}\lfloor\log_{10}(kn)\rfloor . Find the largest value of n for which f(n)\le 300 .

Note: \lfloor x\rfloor is the greatest integer less than or equal to.

Please comment if you have any ideas for creative solutions! I will give hints for this problem in later posts! Have fun with this problem!

Also good luck to all of the girls participating in the Math Prize for Girls next weekend!

Welcome!

Welcome to the wonderful world of mathematics problem solving!

Often times, mathematics problems seem like enormous messes. There are certain questions that we, problem solvers, encounter that do not seem to ever terminate. However, with the knowledge of a few special tricks they fall to pieces and become very elementary. This blog is for people who are interested in messy, difficult-looking, yet very interesting problems. They are not your typical high-school math, “plug and chug” questions. They delve deeper into the concepts that you learn in high-school mathematics. This blog creates an opportunity for you to witness creative solutions and interact with others!

With my personal experience, I have encountered many challenging questions. However, even now I still get discouraged when a problem seems frightening or very messy at first sight. The first time that I took the AIME, question number 14, was a relatively simple problem. However, since it was #14 (out of 15 questions on the AIME contest) and I was still relatively inexperienced, I barely even looked at this problem when I took the contest. The problem seemed challenging with “scary summations”. However, as it turned out, this problem was not bad at all. When I got home, I solved it in about five minutes. Since then, I have been very cautious when it came to “messy-looking” problems because I didn’t want to miss such a chance again.

This blog is for people like me who seek an extension to their mathematics knowledge and the confidence to approach such “scary, messy” problems. I will periodically present tough problems, and explain their solutions showing how the mess turns into a simple, beautiful work of art.

Come join the fun!

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