rt
分享一种解法。∵ρ=lim(n→∞)丨a(n+1)/an丨=lim(n→∞)(2n+1)/(2n+3)=1，∴收敛半径R=1/ρ=1。又，lim(n→∞)丨a(n+1)x^(2n+3)/(an)x^(2n+1)丨=(x-1)²/R<1时，级数收敛。∴其收敛区间为(x-1)²<1，0供参考。
