In the known arithmetic sequence an, A2 = - 6, a1 + A9 = 0, the general formula for finding an

In the known arithmetic sequence an, A2 = - 6, a1 + A9 = 0, the general formula for finding an

∵a1+a9=0
∴a2+ a8=0
∴a8=6
The tolerance of arithmetic sequence is 2,
Then A1 = - 8
∴an=-8+2*(n-1) =2n-10

In the arithmetic sequence {an}, a1 + A9 = 10, then the value of A5 is______ ．

In the arithmetic sequence {an}, if a1 + A9 = 10, then 2a5 = a1 + A9 = 10, ｜ A5 = 5, so the answer is: 5

LGM + LGN = 2lg (m-2n) find the value of log root 2 (M / N)

The original equation is as follows: LG (MN) = LG [(m-2n) ^ 2]  Mn = (m-2n) ^ 2  m ^ 2-5mn + 4N ^ 2 = 0 (m-4n) (m-n) = 0  M = 4N or M = n from LGM, LGN and LG (m-2n): m ＞ 0, n ＞ 0, m-2n ＞ 0  M = n is not suitable, so we should omit  M = 4N  log root 2 (M / N) = log root 2, 4 = log

Who calculates Log1 / 2 {- 1 + radical (1-4a) / 2} = 1
I calculated - 1 / 4, and the answer was - 3 / 4

I'll calculate it for you
1 / 2 = - 1 + root (1-4a) / 2
First general division 1 = - 1 + root (1-4a)
2 = root (1-4a)
4=1-4a
0 3=-4a
a=-3/4