Question

设数列{un}收敛于a,则级数(un-u(n-1))=?)

Answer 1

∑(un-u(n-1))

= (u1-u0) + (u2-u1) + (u3 - u2) + (u4-u3) + ...

= un-u0

= a - u0

其中u0为数列的首项