Question

3^x - 3^(x-1) = 18 then 4^x is equal to

Answer 1

`3^x - 3^(x-1) = 18\\ 3^x-3^x\cdot3^(-1)=18\\ 3^x(1-(1)/(3))=18\\ 3^x\cdot(2)/(3)=18\\ 3^x=27\\ x=3\\\\ 4^x=4^3=64`

Answer 2

`3^x-3^(x-1)=18\\\\3^x-3^x\cdot3^(-1)=18\\\\3^x-(1)/(3)\cdot3^x=18\\\\(2)/(3)\cdot3^x=18\ \ \ /\cdot(3)/(2)\\\\3^x=27\\\\3^x=3^3\iff x=3\\------------------\\4^x=4^3=64\leftarrow answer`