Question 1126255

The following solution solves this problem using the formula:

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

{{{a[n]=7^(n+2)/2}}}

{{{a[n]=(1/2)7^(n+2)}}}

since {{{7^(n+2)=7^3*7^(n-1)}}}, we have

{{{a[n]=(7^3/2)7^(n-1)}}}

{{{a[n]=(343/2)7^(n-1)}}}

=>{{{a[1] =343/2}}} 

=>{{{a[1] =171.5}}} and {{{r=7}}}


first four terms:

{{{a[1] =171.5}}}

{{{a[2] = a*r=(171.5)7=1200.5}}}

{{{a[3] = a*r^2=(171.5)7^2=8403.5}}}

{{{a[4] = a*r^3=(171.5)7^3=117649/2=58824.5}}}