Find the rule: 1,2,4,4 (), 8,64 a 16 b 8 C 12 d 6 A 16 B 8 C 12 D 6 Choose one to fill in the blanks

Find the rule: 1,2,4,4 (), 8,64 a 16 b 8 C 12 d 6 A 16 B 8 C 12 D 6 Choose one to fill in the blanks

a
Odd term * 4
Even term * 2

If a + B + C = 0, 1A + 1 + 1b + 2 + 1C + 3 = 0, then (a + 1) 2 + (B + 2) 2 + (c + 3) 2=______ ．

∵ a + B + C = 0, ∵ (a + 1) + (B + 2) + (c + 3) = 6, the square of both sides is (a + 1) 2 + (B + 2) 2 + (c + 3) 2 + 2 [(a + 1) (B + 2) + (a + 1) (c + 3) + (B + 2) (c + 3)] = 36, and then (B + 2) (c + 3) + (a + 1) (c + 3) + (a + 1) (c + 3) + (a + 1) (B + 3) + (a + 1) (c + 3) + (a + 1) (B + 1) is obtained by removing the denominator from 1A + 1 + 1b + 2 + 1C 3 = 0

Math problem: A. B average is 16, B. C average is 21, then: C-A = how much
Be quick. Be quick, now!
O(∩_ Thank you
Be organized. Be more detailed

A+B=16*2=32 (1)
B+C=21*2=42 (2)
(2)-(1)=C-A=10

The way to solve the problem: 0,1,1 / 4,1 / 2, (), 5 / 64 a.1/8 b.1/4 c.3/16 d.3/8

The general term is [n + (- 1) ^ (n + 1)] / 2 ^ n. when n = 5, it is 3 / 16, and the answer is C