I'm assuming we're working with geometric sequences.
[tex]a_1 = 100, r = -20[/tex]
[tex]T_n = 100(-20)^{n - 1}[/tex]
[tex]T_1 = 100, T_2 = -2000, T_3 = 40000, T_4 = -80000, T_5 = 16 000 000[/tex]
[tex]a_1 = 10, r = -1[/tex]
[tex]T_n = 10(-1)^{n - 1}[/tex]
[tex]T_1 = 10, T_2 = -10, T_3 = 10, T_4 = -10, T_5 = 10[/tex]
