If q = - 1 / 2, then a1 + a3 + A5 / A3 + A5 + A7=

If q = - 1 / 2, then a1 + a3 + A5 / A3 + A5 + A7=

The original formula = (a1 + A2 + a3) / (a1 + A2 + a3) Q & # 178; = 1 / Q & # 178; = 4

If the sum of the first n terms of the equal ratio sequence {an} is Sn, S2 = 4, S4 = 40, then S6 =?

If the sum of the first n terms of the infinite equal ratio sequence {an} is Sn, then S2, s4-s2 and s6-s4 are also equal ratio sequences
Why does the above conclusion have to satisfy the common ratio Q ≠ - 1?
In the same way, what conditions should be satisfied when s2n, s4n-s2n, s6n-s4n are equal? What is the common ratio of the three?

When the common ratio is - 1, the sequence is staggered, and the sum of two adjacent terms is 0,
Such as sequence 2, - 2,2, - 2,2, - 2
S2, S4 - S2, S6 - S4 are all zero, of course, they are not equal
In the same way, the condition of Q ≠ - 1 must be satisfied when s 2n, s 4n-s 2n, s 6n-s 4N are equal ratio sequence
In addition, the common ratio of s2n, s4n-s2n, s6n-s4n is Q ^ (2n)