Respuesta :

irspow
18/72=(ar^-2)/(ar^-4)

1/4=r^2

r=(1/4)^(1/2)

r=1/2

18=a(1/2)^-2

18=4a

9/2=a

y=(9/2)(1/2)^x


wes23465

Answer: 1/2

Step-by-step explanation: hope u got it right