Quadratic equations

301 Views Asked by At

Does anyone know how to find integer solutions of the quadratic equation

$$y^2+y+z=f$$

where $z$ is a fixed odd prime or $1$ and $f$ is a fixed odd prime greater than $3$?

This problem arose from the Diophantine equation $A+B=C$ where $A,B,C$ are natural numbers with no common factor. The managers of this site asked me to make my questions harder for this reason I will restate the above. Does anyone know if the quadratic equation $x^2-2x-[a^5+b^5]=0$ has infinite integer solutions?

2

There are 2 best solutions below

2
On

$$ y^2 + y + z = f $$ $$ y^2 + y + z - f = 0 $$ $$ ay^2 + by + c = 0 $$ where $a=1$, $b=1$, and $c=z-f$. So $$ y = \frac{-b\pm\sqrt{b^2-4ac}}{2a} = \frac{-1\pm\sqrt{1-4(z-f)}}{2} $$ In its method of solution, it's no different from any other quadratic equation.

Whether the solutions are integers depends of course on $z$ and $f$.

0
On

Why dont you express the equation in the form $y^2+y+(z-f)=0$ and use the discriminant $b^2-4ac$ where $a=1$, $b=1$ and $c= z-f$. $c$ could be the difference of two primes or check the sequence. find the possible values of $y$.