Question

a与b互为相反数，c与d互为倒数，求

2a+2b-8

3cd+1

=______．

Answer 1

∵a与b互为相反数，c与d互为倒数，
∴a+b=0，cd=1，
∴原式=

2×0-8

3+1

=-2．
故答案为-2．