Cracking The Code: Mastering The Art of Finding Rational Points

Discover Proven Methods and Techniques for Precision in Rational Point Search” Utilizing geometry and algebra from high school and knowing only one rational point in an elliptic curve, we are able to locate an infinite number of other.

You’re at the top of a long table, preparing to interview for the job you’ve always wanted. You’ve made it to this point and there’s only one more question to be able to.

“Is there a way for the line which runs through the source to go through only reasonable points?”

Five pairs of eyes look at you in anticipation of your answer. Are you up to the task?

You may think that it only happens in stories However, it did happen to me. “Rational Points” are the points in the plane, whose coordinates include all numbers that are rational. For instance, (125,-23), (3,12) and (11, 4) are rational points however (4 2,) and (p 2 – -1) aren’t, as the two numbers are both irrational. 

Rational points are crucial to cryptographers and number theorists and even sit in the midst of some of the more well-known mathematical theorems ever devised. 

The problem before me involved the possibility of a line passing through the source that is, it contains at least one rational point. This is (0 0, 0.). Can it be avoided from going through a different one? I didn’t have the answer immediately so I needed to consider it.

It may seem at first that there is no answer. Near any point in the coordinate plane, there are innumerable rational points within a short distance. With rational points this densely packed, it is almost impossible to imagine a line that could be able to avoid them all.

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As it transpires, it’s possible.

The most important understanding is when you consider how the lines slope. It is possible to think of slope in the form of “rise over run” which is the proportion that changes in the y-coordinate (the “rise”) with the changes within the x-coordinate (the “run”) when you move through the line. 

For example, if found yourself on a line that had slope of m and you have increased the the x-coordinate by one then you must boost by the value of the-coordinate to m in order to stay within the lines. That’s how slope functions.

Imagine starting at (0 0,) along a line that has slope m. Moving 1 to the right and upwards to m will bring you to the line at (1, m). Therefore in the event that the m has a rational value, the line has to pass through another rational point. 

Actually, the numbers (2 2 m), (3, 3 m) and so on have to be in the same line, which indicates how a line traversing the source has a slope that is rational it will pass through an infinite number of rational points.

To answer an interview, you must to think about lines with unnatural slopes. When you have done that you can answer the question right straight away. Consider, for instance, the line that runs through the center with a slope of 2, which is the formula that y= 2 x. If the place ( ab) is located on this line and b is the result, it is the equation b = 2a and for as long as there is there is a zero exists,

we can change the equation as ba =. If ( ab) is an irrational point, then it is not possible: The left-hand part of this equation cannot be rational and the right-hand side, which is 2 is not rational. This means that there cannot be other rational points along this line. (An interesting question for an extension, which we’ll look into in the exercises near the end of the column is: Are there lines in the plane that do not pass through any reasoned points?)

The ability to think quickly about lines has earned me the job. However, mathematicians have been looking at the rationality of points in curves for a considerable time, and they’re discovering the complicated design that these lines have. 

To understand this, let’s take an look at how rational points function on circles within the plane. For simplicity, let’s consider circles that are centered on the center with a radius of r and which have equations that are always

x2 + y2 = r2.

Certain circles do not pass through any rational points. However, if the circle has one rational point it is filled with an infinite number of. Let’s look at the reasons.

Look at the circle that is centered at the center with a radius of. The circle is based on an equation that x 2 + y 2 = 25, and it is home to rational points like (0 5, five) and (3 4, 4) and (3, 4), along with additional points, such as (2 21) and (11, 14). However, knowing only one rational circle point will lead us to many more and we can utilize the information we have learned about lines to discover these lines.

Imagine a line that passes across the point of rationality (0 5,0) in the center of the circle and then let’s say it has a slope of a rational similar to 2. The line will cross the circle at a different point, and then it turns out that this second intersection is the rational point.

Some algebraic equations will tell us the reason. Since the line has a slope of 2 and the y-intercept 5 We can formulate the formula as the equation y = 2 x + 5. The circle’s equation will be 2 + y 2. + 2 + 2. equals 25, therefore to determine the intersection points, we need to do the following equations:

x2 + y2 = 25y = 2x + 5.

One method to resolve this equation is through substitution. Because the equation yequals two + 5 and x = 2+ 5 We could substitute 5+ 5 the number y by using the circular equation to arrive at

x2 + (2x + 5)2 = 25.

You may be tempted to solve this problem with your preferred method However, before we go about that, let’s look at some observations.

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It is first an equation that is quadratic. Quadratic equations contain two solutions, or roots. We already have one since (0 5, 5.) represents a place at which there is an intersection of the line as well as circles, x = 0, which is a formula for our problem. Note that this solution, or root is a rational.

In addition, because all of the values in the equation can be rationalized, if we convert our quadratic equation formula into “standard form” (i.e. the formula ax 2 + bx + c = 0 all coefficients will be rational. A well-known formula known as Vieta’s equation states the quadratic equation that is in normal form the sum of all the roots equals -ba. In this case, the sum is rational. Therefore, when the first root can be rationalized, then the other must be, too.

The two points of intersection are rational and x-coordinates and therefore their “run” between them must be rational. Also, since the line running through them is a rational slope which means the “rise” is rational too. This ensures that the second intersection point is an logical y-coordinate and is therefore the second reasonable point in the circle.

In the case of our experiment, it would have been simpler to solve the equations and locate the other intersection point that happens as the rational point (-4 3). However, the above argument can be generalized extremely well. Consider any line with y equals the sum of mx + b with a slope of rational that runs through the circle to a rational location. The equations system

x2 + y2 = 25
“y” equals MX + b

The quadratic equation is the result of this.

x2 + (mx + b)2 = 25

It contains every rational coefficient. Based on the above argument that if the line goes through the circle and again, the second point of intersection has to be rational. Therefore, if you have a sensible point within a circle you will be able to find endless other points by drawing an unidirectional line by traversing the line through your rational spot, and then finding the second points of intersection.

The same approach can be used to identify the rational points of”elliptic curves. They can be described as “cubic” curves that have equations with variables that are elevated to the third order. 

They’re more complicated than circles and lines and are of particular importance to number theorists and cryptographers. Studying elliptic curves was a key factor in the resolving the problem Fermat’s Last Theorem — an theorem about finding infinity angles on specific curves which was verified to be correct by Andrew Wiles in the 1990s (about 350 years after Pierre de Fermat famously claimed in the margins of a math textbook the existence of a gorgeous proof, but his margins were too narrow for it to be contained the proof).

There are many kinds of Ellipsic curves. Here’s an example of a basic one:

y2 = x3 – 4x + 1.

Here is the graph on the plane:

Although it’s not clear that there are numerous rational points to this curve. For instance, (0, 1) and (4 7) both fall on this curve, as

One 2 = 0 3 – 4 x 0 + 1.


7. 2 = 4 3 + 4 x 4 + 1.

As with circles, there’s an inventive method of using these rational points to discover more about the curve. The secret is to employ lines.

The equation for the line between (0 1,) ((0), 1) and (4 7) is straightforward enough to determine The slope is the variation in the value of y with the increase in the value of x (or the equation m = 7-14-0 = 64 = and since the line goes through (0 1, 1) the slope is 0. its-intercept is one. The equation for the line that runs through these 2 points that y = 32 x+ 1. Below is the graph of the line, along with the elliptic curve

Note that the line intersects the elliptic curve three times: at (0, 1), (4, 7) (0 1, 0), (4, 7) and a third unidentified point. It is evident that the third point has to also be rational.

Take the elliptic curve or line, as set of equations:

y2 = x3 – 4x + 1
“y” equals 32 x + 1.

We can make substitutions just as we did with the circle and line. This is what we get:

(32x+1)2 = x3 – 4x + 1.

It is an inverse cubic problem with rational coefficients. A cubic equation could be composed of up to three real solutions which makes sense since we’re trying to find 3 points where the intersection occurs. We already have two of them: x = 0, which is the number (0 1, 1) and the third one is x equals 4, and is the number (4 7, 7).

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So, we are aware that two of the three possible solutions are rational. What happens to the third? As it was with our quadratic equation Vieta’s formula assures that the root of this cubic equation has to be rational.

Therefore, when two options are rational then the third must be, as well. This will lead us to a sensible point in the elliptic curve. It’s not too difficult to solve our cubic equation, and then find the third intersection point that is (-74,-138). Similar to circles, the argument can be generalized to the following: If a line intersects our elliptic curvature at two points that are rational, then the third intersection is also rational.

This technique is extremely effective when paired with another great characteristic of this elliptic curve. It is evident how the curve is perfectly symmetric with respect to the x-axis The bottom portion of the graph is an reflection of the top. This means that when there is a point ( ab) is located on the curve, then the location ( a, — B) must be located on the curve. Therefore, if(-74,-138) lies on the curve, then so is (-74,138).

This symmetry is more than simply provide us with an additional rational edge on the curvature. It also gives us a brand new pair of points that we can run the line through.

The line that runs through two rational points (-74,138) along with (0 1, 1)) is another rational point along the curve. It is possible to take that point and repeat the process and search for further rational points. 

This technique has been used by mathematicians to develop elliptic-curve cryptography, which is a method of creating secret codes based on their structure to create rational points the elliptic curves. 

It’s easy to utilize this technique to locate some rational areas on the curve however, if you’re only presented with a rational point it’s difficult to pinpoint exacoptly where the process started. This type of reverse-resistant process is vital to create safe secret code.

The complex design of points that are rational on the elliptic curve is an active subject of mathematic research. Beginning at the point (0 1,0) we came up with an infinite listing of rational points along the curve y2 = 3x + 4x + 1 each of which may help us find the other. However, there are other. 

There is a rational number (-1 2, 2) is located on the curve, but it’s not listed on the list, and we could use it to create an infinite number of rational points based on the basis of y2 = 4xx x3 + 1. It is apparent that each rational point on the curve is a blend of these two points, meaning that it is the “rank” for the curve will be 2.

Two beginning points are all required to create the rational points that make up the curve. Mathematicians are currently studying how curve ranks work similar to this, and it’s not yet clear if there exists any maximum rank for elliptic curves.

Beginning with the quest for inequalities to equations, 2,000 years ago, to Fermat’s Last Theorem to elliptic-curve cryptography Today The study of rational points begins at the high-school level with algebra, geometry, and will lead to advanced mathematics in a stunning and gratifying manner. It could even assist you in landing the job you’ve always wanted to have.

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1. Find the equation for the line that runs through a rational point.

2. The numbers (0 1,) and (4 7,) both are located on the elliptic curve, y2 = x3 + 4x + 1. the equation for the line that connects them is y = -2x + 1. But the equations are not exactly the same.

“y” = 2 + 1 + 1
y2 = x3 – 4x + 1

There are only two real alternatives. What is the reason this doesn’t conflict with the argument in this column?

3. Find out that the circle with equation 3x 2 + y 2 = 3 travels through the absence of rational points.

4. Is there a third intersection point between the line (-74,138) (-74,138) (0 1,) and the curvature of the elliptic curve y2 = 3x + 4x? (Warning this is only for mathematicians and algebraic lovers!)

Cracking The Code: Mastering The Art of Finding Rational Points, News, Math

Click to see Answer 1.

An easy response can be found by calculating the equation y + 2. Each point along that line is going to have an an y-coordinate of 2 so every point is rational. An interesting question is that x + y = 2. Do you understand the reason why this line has no rational arguments?

Click here to find Answer 2.

The line that y = 2x + 1 is connected to the elliptic line at (0 1, 1) which means that this equation (-2x + 1)2 = x3 + 4x + 1 is an x-repeated root = 0.

It’s simple to solve this problem by simplifying and incorporating:

(-2x+1)2 = x3 – 4x + 1
4×2 – 4x + 1 = x3 – 4x + 1
0 = x3 – 4x2
0 = x2 (x – 4).

Since 2 in 2 appears in the form of a factored version of the cubic, the equation of x = 0 is an multiplicity of 2. In reality that’s how you begin your search for the rational point on elliptic curves.

Find one rational point, and then look up the equation for the tangent line, and then see where it intersects with the curve once more. Because the point at which tangency occurs has double-rooted the third root that is the one that corresponds to the second point of intersection should be rational.

Also Read: Unlocking Wonderland’s Mathematical Secrets: A Beginner’s Guide To Alice in Wonderland

Click to see the Answer 3.

Let’s say the circle travels over the logical points (mn,pq) where m, n and Q are all integers. the pq and mn are both in the simplest terms (i.e. they do not have any factors that are in common) and both q and n are positive. This means that (mn)2 + (pq)2 = 3.

We’ll first show that the number n equals the number q. We have M2 + n2(pq)2 = 3n2, and because the numbers 3n2 as well as m2 both are integers, the result is n2(pq)2. Because both p and Q do not share common factors, it follows that the q must be divided by the number n

Similar reasoning based on the equation Q2 (mn)2 + 3q2 proves that n must be divided by the number q. Because the numbers n and the number q are both positive integers which divide one another this must be the scenario that the number n is equal to Q.

Therefore, (mn)2 + (pn)2 = 3 and, therefore 3n2 = m2 + p2. The right-hand part of the equation is divided by three, which means that the left-hand side should also have a divisor of three. 

One interesting aspect of the perfect square is that each perfect square is more than three or is three times as many. (This can be demonstrated by through modular math.) The only way that the sum of two perfectly squares could be a multiple of 3 is when each perfect square is more than three.

Therefore, that m 2 and p 2 are each divisible by 3. Because 3 is an integer This implies that the numbers m and the number p are each divisible by 3, which means that the left part of the equation is actually divisible by 9. 

The right-hand part of the equation is divided by 9, so the equation must be divisible by 3. However, this is in contradiction to the notion that mn exists in the lowest terms. Therefore, there is no reason to believe that the equation x 2. + y 2 = 3.

A stimulating, and difficult extension problem is: For which numbers of k can the equation x2+y2 = k go through rational points?

Click to see Answer 4.


The line is characterized by the equation the equation y = -514x + 1. To determine the x-coordinate, find the formula (-514x+1)2 = x3 + 4x + 1. To be honest, I just had Wolfram Alpha do it.


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