等比级数a+aq+aq^2+…+aq^(n-1)+…(a≠0)()
A.当|q|1时收敛
C.当|q|≤1时收敛;当|q|>1时发散
D.当|q|
AP=A/r
BP=A/(r-s)
CP=A/r+B/r2
DP=A/(r+s)