2^x+3*3^x+4=18

=> 2^x+3*3^x=18-4

=> 2^x+3*3^x=14

=> 2^x + 3^(x+1) = 14

putting x=1 in the equation above gives left hand side = 2 + 3^2 = 11

putting x=2 in the equation above gives left hand side = 2^2 + 3^3 = 31

Now, this means the value of x is between 1 and 2

on solving the equation gives x = 1.2346611