geometric sequence
[tex]a_n=a1r^{n-1}[/tex]
r=common ratio
a1=first term
n=which term
2nd term is 50
4th is 112.5
[tex]a_2=a1r^{2-1}[/tex]=50
[tex]a_2=a1r^{4-1}[/tex]=112.5
50=[tex]a1r^{1}[/tex]
112.5=[tex]a1r^{3}[/tex]
therefor
112.5/50=[tex] \frac{a1r^3}{ar^1} =r^2[/tex]=2.25
r^2=2.25
sqrt both sides
r=1.5
the common ratio is 1.5
