a-1/8 * 6^n=2^n
suy ra 1/8*6=2
suy ra n=1
b- 27<3^n<243
= 3^3<3^n<3^5
suy ra 3^n=3^4
suy ra n=4
a) \(\frac{1}{8}.16^n=\frac{16^n}{8}\)
\(\frac{16^n}{8}=2^n\)
\(\frac{1}{8}.16^n-2^n=0\)
\(\frac{16^n-8.2^n}{8}=0\)
\(16^n-8.2^n=0\)
\(n\)\(=1\)
b)
\(\Leftrightarrow3^3<3^n<3^5\)
\(\Leftrightarrow n=4\)
Tik nh huyenheo823
a)1/8*16n=2n
2n/16n=1/8
(2/16)n=1/8
(1/8)n=1/8
vậy n=1
b)27<3n<243
33<3n<35
do đó 3<n<5
nên n=4
vậy n=4