Question 977413
{{{a[n] = a[1]*(r)^(n-1)}}}


{{{a[n] = -3*(r)^(n-1)}}} Replace {{{a[1]}}} with {{{-3}}}


{{{a[n] = -3*(2)^(n-1)}}} Replace {{{r}}} with {{{2}}}


and that's all there is to it