Question

已知:lab-2l与lb-1l互为相反数

Answer 1

lab-2l与lb-1l互为相反数,则|ab-2|+|b-1|=0

则ab-2=0,b-1=0

则a=2,b=1

原式=1/2×1+1/3×2+1/4×3+……+1/2008×2007

=(1-1/2)+(1/2-1/3)+(1/3-1/4)+……+(1/2007-1/2008)

=1-1/2+1/2-1/3+1/3-1/4+……+1/2007-1/2008

=1-1/2008

=2007/2008