\(3^{-1}.3^n+6.3^{n-1}=7.3^6\) dung the nay ko?
dung thi k toi vao giai ko dung cung k roi sua de
3\(^{-1}\). 3\(^n\)+ 6.3\(^{n-1}\) =7.3\(^6\)
= 3\(^{-1+n}\)+ 6.3\(^{n-1}\)=7.3\(^6\)
= 3\(^{n-1}\)+ 6.3\(^{n-1}\)=7.3\(^6\)
=3\(^{n-1}\). 7=7.3\(^6\)
=3\(^{n-1}\)=3\(^6\)
n-1=6
n=7