Question 866098
r=-1/3
i) Tn = 2/3 *(-1/3)^(n - 1)
Tn = 2/3 *(-1/3)^(9)=-2/59049 
Tn = 2/3 *(-1/3)^(7)=-2/6561 
ii) D=2/3 *(-1/3)^(9)-2/3*(-1/3)^(7)=16/59049