Question

[nguyen thao van]

tim m,n nguyen duong de 

9^m-3^m=n^4+2n^3+n^2+2n

Answer 1

[nguyen thao van]

dat 3^m=a(a_{^{>0)  ta co}}

_^{a^2-}a=n^4+2n^3+n^2+2n

de thay (2n^2+n)^2<(2a-1)^2<(2n^2+n+2)^2

suy ra (2a-1)^2=(2n^2+n+1)^2

phan sau tu lam nhe