(Ⅰ)求函数f(x)= |3x+2|−|1−2x||x+3| 的最大值M.
(Ⅱ)若实数a,b,c满足a2+b2≤c≤M,证明:2(a+b+c)+1≥0,并说明取等条件.
— is your birthday?
— It's on 25th September.
单项式-23x2y3的次数是( )