If a is a positive integer, then 2^a + 2^(a + 1)+ 2^(a + 2)+ 2^(a + 3)+ 2^(a + 4)+ 2^(a + 5)+ 2^(a + 6) =
Choose the correct choice:	A) 3^(a + 1)	B) 2^(a + 1)	C) 2a	D) 2a^(a + 1)	E) 127(2^a)
If a is a positive integer, then 2^a + 2^(a + 1)+ 2^(a + 2)+ 2^(a + 3)+ 2^(a + 4)+ 2^(a + 5)+ 2^(a + 6) =   2^a(1+2+4+8+16+32+64)   2^a(127)   E. 127(2^a)
<result>E</result>
If a is a positive integer, then 2^a + 2^(a + 1)+ 2^(a + 2)+ 2^(a + 3)+ 2^(a + 4)+ 2^(a + 5)+ 2^(a + 6) =