If the sequence $${x}_{1}$$, $${x}_{2}$$, $${x}_{3}$$, ..., $${x}_{n}$$, ... is such that $${x}_{1}={3}$$ and $${x}_{n+1}={2}{x}_{n}-{1}$$ for $$n\ge 1$$, then $${x}_{20}-{x}_{19}=$$
-
A$${2}^{19}$$
-
B$${2}^{20}$$
-
C$${2}^{21}$$
-
D$${2}^{20}-{1}$$
-
E$${2}^{21}-{1}$$
显示答案
正确答案: A