# Questions tagged [diophantine-equations]

Questions on the use of Mathematica to find integer/rational solutions to equations.

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### FrobeniusSolve with solutions only being 0 or 1 being acceptable

I want an EFFICIENT way of solving the Frobenius Equation a1 n1 + a2 n2 + a3 n3 + ... + aK nK = U where n1, n2, ..., nK are restricted to be either 0 or 1. I ...
165 views

### How do I declare a countably infinite list of variables as being integers?

I want to do this, Solve[ { n1 + n2 + n3 + .... = 10, n1 + 2 n2 + 3 n3 + .... = 100}, {n1,n2,n3,....}, Assumptions -> {n1,n2,n3,.... are Integers >=0} ] ...
868 views

### Why does Solve lock up when trying to solve the quadratic equation with large integers?

Why does Solve lock up when trying to solve the equation ...
87 views

### Unexpected omission by Wolfram Alpha [closed]

When Alpha is submitted the equation $a(a^2-1)=2b^2$, it unexpectedly forgets the integer solution $a=1,b=0$. What could explain this ? http://www.wolframalpha.com/input/?i=a(a%5E2-1)%3D2b%5E2
119 views

### On the solvability of the Diophantine equation $a(x^2-y^2)+2bxy=1$

Take two integers $a,b$ with $\mathrm{GCD}(a,b)=1$ and $a$ odd. Consider the Diophantine equation $$a(x^2-y^2)+2bxy=1,\qquad x,y\in\mathbb Z$$ Is there any efficient way to determine whether such ...
732 views

### How can I reduce the time to run this code?

I am trying to find the integers $a, b, c, d \in [-15, -1] \cup [1, 15]$ so that the equation $\left| x^2 + a x + b \right| = c x + d$ has four distinct integeral solutions different from $0$. ...
95 views

### Guess Diophantine equation from its solutions

Take for example the equation $$n^2=x^2+y^2+1$$ where $x,y$ are integers. This equation admits solutions only for some values of $n$, to wit, $$n=1,3,9,17,19,33,35,51,73,81,99,\dots$$ Can we ...
268 views

### Finding Smallest Positive Solution to Diophantine Equation

Mathematica can solve $v^2- d u^2=4$ quickly, even for nonsmall $d$: d = 400004; Reduce[v^2 - d u^2 == 4, Integers] d = 400012; Reduce[v^2 - d u^2 == 4, Integers] ...
81 views

### How do we show reduction steps?

This produces 3 equivalent Diophantine equations. How can we show the reduction steps? I need to do this for a paper. ...
424 views

### Efficient way to solve equal sums $x_1^k+x_2^k+\dots+x_5^k=y_1^k+y_2^k+\dots+y_5^k$ with Mathematica?

I need to solve the system of equations, call it $S_1$, in the integers $$x_1x_2x_3x_4x_5 = y_1y_2y_3y_4y_5$$ $$x_1^k+x_2^k+\dots+x_5^k=y_1^k+y_2^k+\dots+y_5^k,\;\; k= 2,4,6$$ I used a very ...
642 views

176 views

### find and count the number of solutions without multiplicity in Solve?

I would like to solve a Diophantine equation and find its solution, but I need only count one time for each $a$, i.e., when for some $a$ it found some $x,y,z$, then go to the next $a$. more precisely ...
237 views

### Solve an exponential equation in integers

Find two integers x and y such that $x^y +y^x = 94032$. I have used ...
827 views

### Partitioning a number into consecutive integers

Consider n=45; then $$1+2+3+4+5+6+7+8+9=45$$ $$5+6+7+8+9+10=45$$ $$7+8+9+10+11=45$$ $$14+15+16=45$$ $$22+23=45$$ Question: how to find all representations of a ...
3k views

### How can I solve the equation with integers as a solution?

I want to solve the equation $$(x-1)^2 + (y-1)^2 + (z-1)^2 = 49$$ where $x$, $y$, $z$ are integer and $x \neq 1$, $y \neq 1$, $x \neq 1$. How do I tell Mathematica to do that?
84 views

### diophantine linear equation with condition on the sum of coefficients [closed]

I am trying to solve the following diophantine equation x*a + y*b == c where a,b,c are integers and the absolute value of their sums is, for instance, 4. Then I ...