我是真没看明白第一题……
2、原式=1/3×(1+1/1+2+1/1+2+3+1/1+2+……+33)=1/3×(2/1×2+2/2×3+……+2/33×34)
=2/3×(1-1/34)=11/17
3、原式=1-1/2+1-1/4+1-1/8+……+1-1/256
=8-(1/2+1/4+1/8+……+1/256)
=8-(1-1/256)
=7又255/256对不起,第一题没说清,^是平方,*是乘号我说嘛~~原式=1+1/2×4+1+1/4×6+……+1+1/10×12=5+1/2×(1/2-1/4+1/4-1/6+……+1/10-1/12)=5+1/2×(1/2-1/12)=5又5/24