幂级数∑n=0∞(-1)n•[1/(2n+1)](x/3)n的收敛半径R=____．
3。解析：由于limn→∞1/[3n+1(2n+3)]/{1/[3n(2n+1)]}=limn→∞(2n+1)/[3(2n+3)]=1/3所以R=3．
幂级数∑n=0∞(-1)n•[1/(2n+1)](x/3)n的收敛半径R=____．
3。解析：由于limn→∞1/[3n+1(2n+3)]/{1/[3n(2n+1)]}=limn→∞(2n+1)/[3(2n+3)]=1/3所以R=3．
