Question 1164875
f(x)=ab^x
18=ab^2
162=ab^4
so b^2=18/a
and therefore b^4=324/a^2
162 = 324/a
a=2

if a=2 then 18=2b^2 and b^2=9 and b=3
check with a=4 and 162=2*81=162 checks

the equation is f(x)=2*3^x
{{{graph(300,300,-5,6,-10,200,2*3^x)}}}