A:They are talking about how to make salad.
B:They are taking an order in a restaurant.
C:They are eating salad.
产品生产环节中,附加值最低的环节是( )
设a,b,c都是正数,求证:bca+cab+abc≥a+b+c .
已知等比数列{an}满足2a1+a3=3a2,且a3+2是a2,a4的等差中项.
(Ⅰ)求数列{an}的通项公式;
(Ⅱ)若bn=an+log21an,Sn=b1+b2+…bn,求使 Sn﹣2n+1+47<0 成立的正整数n的最小值.