(Ⅰ)求证:C=2A;
(Ⅱ)求a,b,c.
(Ⅰ)求数列{an}的通项公式;
(Ⅱ)若 ,证明: .
(Ⅰ)求f(x)的最小正周期和最大值;
(Ⅱ)若 ,画出函数y=g(x)的图象,讨论y=g(x)﹣m(m∈R)的零点个数.
(Ⅰ)求证:a2 , a8 , a5成等差数列;
(Ⅱ)若等差数列{bn}满足b1=a2=1,b3=a5 , 求数列{an3bn}的前n项和Tn .
(Ⅰ)求函数f(x)的单调区间;
(Ⅱ)若k为差数,当x>0时,(k﹣x)f'(x)<x+1恒成立,求k的最大值(其中f'(x)为f(x)的导函数).
(Ⅰ)求实数m的取值范围;
(Ⅱ)若f(x1)=f(x2)(x1≠x2),求证:x1+x2>2.