Question 1187236
the first term  is {{{a[1]=300 }}}
 the fourth term is {{{a[4]=-8/5}}}

the {{{n}}}th term formula is:

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

find  the common ratio 

{{{a[4]=a[1]*r^(4-1)=-8/5}}}

{{{a[4]=a[1]*r^3}}}

{{{a[4]=300*r^3}}}

{{{300*r^3=-8/5}}}

{{{r^3=(-8/5)/300}}}

{{{r^3=-2/375}}}

{{{r=root(3,-2/375)}}}

{{{r=root(3,-2/375)}}}

{{{a[n]=300*(root(3,-2/375))^(n-1)}}}


{{{sum(300(root(3,-2/375))^(n-1),n=1,infinity )}}}=> converges