Show that
∑r=112(3r+7+2r)=8508\sum_{r=1}^{12} \left(3r + 7 + 2^r\right) = 8508∑r=112(3r+7+2r)=8508
A sequence u1,u2,u3,… u_1, u_2, u_3, \dots\,u1,u2,u3,… is defined by
u1=25\displaystyle u_1 = \frac{2}{5}u1=52, un+1=1un\displaystyle u_{n+1} = \frac{1}{u_n}un+1=un1
Find the exact value of ∑r=1100ur\sum_{r=1}^{100} u_r∑r=1100ur.