19.3.35 Linear Operators

Condition: prove the limited operator. \ [A \ Left (X_ {1}, X_ {2}, \ LDOTS \ RIGHT) (T) = \ SUM_ {K = 1}^{EFTY ON ON {X_ {K} T LEA {3^{K} +1}, ELS \ QUADA A: l_ {2} \ rightarrow C [1; 2] \]