- #1
spacetimedude
- 88
- 1
Homework Statement
Find all solutions x,y∈ℤ to the following Diophantine equation:
x^2-x=y^3
Homework Equations
The Attempt at a Solution
Hello. I am stuck in the last part of finding the solutions.
I rearranged x^2-x=y^3 into x(x-1)=y^3. The Fundamental Theorem of Arithmetic tells that since x and x-1 are coprime, and the multiple of the two is a cube, x and x-1 themselves have to be cubes.
Note that the difference of the two is 1.
Hence, looking through the list of possible cubes, ...-8, -1,0,1,8... we can see that the cubes with difference of 1 are -1 and 0, and 0 and 1.
My question arises here.
Do I set (x-1) and x equal to the two pairs?
So Pair 1:
(x-1)=-1 =>x=0
x=0
and
Pair 2:
(x-1)=0 => x=1
x=1.
Is this correct?