Đáp án + Giải thích các bước giải:
e)
`3^(x+1)+3^(x+2)+3^(x+3)=117`
`=>3^(x+1) .(1+3+3^2)=117`
`=>3^(x+1).13=117`
`=>3^(x+1)=9`
`=>x+1=2`
`=>x=1`
f)
`(x-4)^3=x-4`
`=>(x-4)^3-(x-4)=0`
`=>(x-4)[(x-4)^2-1]=0`
`=>`\(\left[ \begin{array}{l}x-4=0\\(x-4)^2-1=0\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}x=4\\(x-4)^2=1\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}x=4\\x-4=1\\x-4=-1\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}x=4\\x=5\\x=3\end{array} \right.\)
Vậy `x\in{3;4;5}`
