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solve-in-Z-x-3-6y-3-4z-3-




Question Number 35291 by 123 45 polytechnicien last updated on 17/May/18
solve  in Z  x^3 +6y^3 =4z^3
solveinZx3+6y3=4z3
Commented by 123 45 polytechnicien last updated on 17/May/18
why z=x+iy and nota+ib ?
whyz=x+iyandnota+ib?
Answered by ajfour last updated on 17/May/18
4(x+iy)^3 =x^3 +6y^3   4(x^3 −iy^3 +3ix^2 y−3xy^2 )=x^3 +6y^3   ⇒ y^3 =3x^2 y    ....(i)  ^�  and  x^3 −4xy^2 −2y^3 =0     ....(ii)  (i)⇒  y=0  or y^2 =3x^2   using above  (ii)⇒  x=0  or         −11x^3 =2y^3   or      −11x=6y  inconsistent , so  only solution is  (0,0) .
4(x+iy)3=x3+6y34(x3iy3+3ix2y3xy2)=x3+6y3y3=3x2y.(i)¯andx34xy22y3=0.(ii)(i)y=0ory2=3x2usingabove(ii)x=0or11x3=2y3or11x=6yinconsistent,soonlysolutionis(0,0).

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