Đáp án + Giải thích các bước giải:
a)
`3^(n+1):9=27`
`=>3^(n+1):3^2=3^3`
`=>3^(n+1)=3^3. 3^2`
`=>3^(n+1)=3^5`
`=>n+1=5`
`=>n=5-1`
`=>n=4`
b)
`3^2. 3^n=3^7`
`=>3^n=3^7:3^2`
`=>3^n=3^5`
`=>n=5`
c)
`2^(2n-3)=2.4^3`
`=>2^(2n):2^3=2.(2^2)^3`
`=>2^(2n)=2.2^6. 2^3`
`=>2^(2n)=2^10`
`=>2n=10`
`=>n=10:2`
`=>n=5`
d)
`6^(n+1)=6^18:6`
`=>6^n. 6=6^17`
`=>6^n=6^17:6`
`=>6^n=6^16`
`=>n=16`
e)
`3^(n+4). 3^(2n):81=27^6`
`=>3^(n+4). 3^(2n):3^4=(3^3)^6`
`=>3^(n+4+2n)=3^18. 3^4`
`=>3^(3n+4)=3^22`
`=>3n+4=22`
`=>3n=22-4`
`=>3n=18`
`=>n=18:3`
`=>n=6`
