问题
选择题
设函数f(x)满足2f(n+1)=2f(n)+n,f(1)=2,则f(5)=( )
A.6
B.6.5
C.7
D.7.5
答案
∵函数f(x)满足2f(n+1)=2f(n)+n,f(1)=2,
∴f(2)=f(1)+
=1+1 2
=1 2
,3 2
f(3)=f(2)+1=
+1=3 2
,5 2
f(4)=f(3)+
=3 2
+5 2
=4,3 2
f(5)=f(4)+2=4+2=6.
故选:A.