—_______?
—Pretty good! How about you?
A:How do you do
B:What are you doing
C:Where are you from
D:How are you doing
如 图(1)
给出如下结论:
①对任意m∈Z,有f(2m)=0;
②函数f(x)的值域为0,+∞);
③存在n∈Z,使得f(2n+1)=9;
正确的有( )
(Ⅰ)求角 B 的大小;
(Ⅱ)若 b=23 ,求 a+c 的最大值.