Answer:
Step-by-step explanation:
[tex]Use\\\\a^n\cdot a^m=a^{n+m}\\\\\dfrac{a^n}{b^n}=\left(\dfrac{a}{b}\right)^n\\=================\\A.\ 3^{x+1}=3^x\cdot 3\neq3^x\\\\B.\ 3\cdot3^{x-1}=3\cdot3^x\cdot3^{-1}=(3^1\cdot3^{-1})\cdot3^x=3^{1+(-1)}\cdot3^x=3^0\cdot3^x=1\cdot3^x=3^x\\\\C.\ \dfrac{18^x}{3}\neq3^x\\\\D.\ \left(\dfrac{18}{6}\right)^x=(3)^x=3^x\\\\E.\ x^3\neq3^x\\\\F.\ \dfrac{18^x}{6^x}=\left(\dfrac{18}{6}\right)^x=(3)^x=3^x[/tex]
