Question 967305


{{{a[n]=(-1)^(n(3n+2))}}},

if you need fifth term {{{a[5] }}}, means {{{n=5}}}; so, substitute it in given formula

{{{a[5]=(-1)^(5(3*5+2))}}}

{{{a[5]=(-1)^(5(15+2))}}}

{{{a[5]=(-1)^(5(17))}}}

{{{a[5]=(-1)^(85)}}}....since {{{85}}} is an odd number we will have negative sign

{{{a[5]=-1}}}