Question 1154845

{{{a(n) = a(1)* r^(n-1)}}}

a(5) = a(1)*r^4
a(7)= a(1)*r^6

32 = a(1)*r^4
128= a(1)*r^6

r^6/r^4 = 128/32

r^2 =4

r=+/-2

Plug r 

in 32 = a(1)*r^4

32 = a( 1)*16

a1=2