For every point on the plane, one of $ n$ colors are colored to it such that:
$ (1)$ Every color is used infinitely many times.
$ (2)$ There exists one line such that all points on this lines are colored exactly by one of two colors.
Find the least value of $ n$ such that there exist four concyclic points with pairwise distinct colors.
Let $ f$ be a function given by $ f(x) = \lg(x+1)-\frac{1}{2}\cdot\log_{3}x$.
a) Solve the equation $ f(x) = 0$.
b) Find the number of the subsets of the set \[ \{n | f(n^{2}-214n-1998) \geq 0,\ n \in\mathbb{Z}\}.\]
Let $ n$ be a positive integer and $ [ \ n ] = a.$ Find the largest integer $ n$ such that the following two conditions are satisfied:
$ (1)$ $ n$ is not a perfect square;
$ (2)$ $ a^{3}$ divides $ n^{2}$.
The inradius of triangle $ ABC$ is $ 1$ and the side lengths of $ ABC$ are all integers. Prove that triangle $ ABC$ is right-angled.
Joe is playing with a set of $6$ masses: $1$g, $2$g, $4$g, $8$g, $16$g, and $32$g. He found that some weights can be measured in more than one way. For example, $7$g can be measure by putting $1$g, $2$g, and $4$g on one side of a balance. It can also be achieved by putting $1$g and $8$g on different sides of a balance. He therefore wonder which weight can be measured using these masses in the most number of different ways? Can you help him to find it out? Describe how will you approach this problem. The final answer is optional.
As shown below, $ABCD$ is a unit square, $\angle{CBE} = 20^\circ$, and $\angle{FBA} = 25^\circ$. Find the circumstance of $\triangle{DEF}$.
Find all the Pythagorean triangles whose two sides are consecutive integers.
Find all the positive integer triplets $(m, n, k)$ that satisfy the equation $$1!+2!+3!+\cdots+m!=n^k$$
where $m, n , k > 1$
Solve in positive integers the equation $x^2 + y^2 = z^4$, where $\gcd(x,y)=1$ and $x$ is even.
Show that the sum and difference of two squares cannot be both squares themselves.
If for a given positive integer $n$, the equation $x^n + y^n = z^n$ is not solvable in positive integer. Show that the equation $$x^{2n} + y^{2n} = z^{2n}$$
is not solvable in positive integers either.
Show that the equation $$x^2 + y^2 -19xy - 19 =0$$ is not solvable in integers.
Solve in positive integers $$x^3 + y^3 + z^3 = 3xyz$$
What is the minimal number of masses required in order to measure any weight between 1 and $n$ grams. Note that a mass can be put on either sides of the balance.
Compute the value of $\sin{18^\circ}$ using regular geometry.
Let $F$ be a point inside $\triangle{ABC}$ such that $\angle{CAF} = \angle{FAB} = \angle{FBC} = \angle{FCA}$, show that the lengths of three sides form a geometric sequence.
Suppose the point $F$ is inside a square $ABCD$ such that $BF=1$, $FA=2$, and $FD=3$, as shown. Find the measurement of $\angle{BFA}$.
Solve this equation in positive integers $$x^3 - y^3 = xy + 61$$
Solve in integers the equation $$(x+y)^2 = x^3 + y^3$$
Let $k$ be a positive integer, show that $(4k+3)$ cannot be a square number.
How many numbers in this series are squares? $$1, 14, 144, 1444, 14444, \cdots$$
Find all positive integer $n$ such that $n$ is a square and its last four digits are the same.
Solve the following equation in positive integers: $15x - 35y + 3 = z^2$
Find a four-digit square number whose first two digits are the same and the last two digits are the same too.
Solve the following equation in positive integers: $3\times (5x + 1)=y^2$