已知定义在R上的函数f(x)满足f(x)=-f(x+3/2),且f(-2)=f(-1)=-1,f(0)=2,f(1)+f(2)+...+f(2009)=
问题描述:
已知定义在R上的函数f(x)满足f(x)=-f(x+3/2),且f(-2)=f(-1)=-1,f(0)=2,f(1)+f(2)+...+f(2009)=
答
f(x)=-f(x+3/2)=-[-f(x+3)]=f(x+3)
f(x)为周期函数f(1)+f(2)+f(3)++f(1+n*3)+f(2+n*3)+f(3+n*3)
答
因为f(x)=-f(x+3/2)=f(x+3),所以f(-2)=f(-2+3)=-1,f(-1)=f(-1+3)=-1,f(o)=f(0+3)=2,f(I)=f(1+3)=-1..........f(2006)=f(2006+3)=-2,(2009+1)/3=670没余数,f(0)+f(1)+f(3)=0,那可计算出f(1)+f(2)+f(3)+........f(2008)+f(2009)=-2
答
f(x)=-f(x+3/2)=-[-f(x+3)]=f(x+3)
f(1)+f(2)+...+f(2009)=669[f(-2)+f(-1)+f(0)]+f(-2)+f(-1)=-2