Suppose there exist integers x and y such that x4+x3+x2+x=y6+61.
Let us consider the equation modulo 7.
First, note that y6≡0 or 1(mod7) for any integer y, since by Fermat's Little Theorem, y6≡1 if y is not divisible by 7, and 0 otherwise.
So y6≡0 or 1(mod7).
Now, 61≡5(mod7), so y6+61≡5 or 6(mod7).
Therefore, x4+x3+x2+x≡5 or 6(mod7).
Let us compute x4+x3+x2+x(mod7) for all x=0,1,2,3,4,5,6:
- x=0: 04+03+02+0=0
- x=1: 1+1+1+1=4
- x=2: 16+8+4+2=30≡2(mod7)
- x=3: 81+27+9+3=120≡1(mod7)
- x=4: 256+64+16+4=340≡4(mod7)
- x=5: 625+125+25+5=780≡3(mod7)
- x=6: 1296+216+36+6=1554≡1(mod7)
So the possible residues are 0,1,2,3,4 modulo 7.
But y6+61≡5 or 6(mod7), which are not among the possible residues for x4+x3+x2+x.
Therefore, there are no integer solutions to the equation.