Question 700036
{{{a[1]}}}=first term
{{{r}}}=common ratio
{{{a[n]=a[1]*r^(n-1)}}}
{{{a[8]=a[1]*r^7}}}
{{{a[4]=a[1]*r^4}}}
{{{a[8]/a[4]}}}={{{a[1]*r^7/(a[1]*r^4)}}}={{{r^3}}}
{{{a[8]=384}}} and {{{a[4]=48}}}
{{{r^3=384/48=8=2^3}}}
{{{highlight(r=2)}}}
Substituting {{{r=2}}} and {{{a[4]=48}}} into {{{a[4]=a[1]*r^4}}} we get
{{{48=a[1]*2^4}}} --> {{{48=a[1]*16}}} --> {{{48/16=a[1]}}} --> {{{highlight(a[1]=3)}}}
Substituting {{{r=2}}} and {{{a[1]=3}}} into {{{a[n]=a[1]*r^(n-1)}}} we get
{{{highlight(a[n]=3*2^(n-1))}}}