121 *3/4-3/8*40-0.75 (1/8+1/24+1/48+1/80+1/120+1/168)*56
3个回答

1. 121*3/4-3/4*1/2*40-3/4

=(121-1/2*40-1)*3/4

=(120-20)*3/4

=100*3/4=75

2.(1/8+1/8*1/3+1/8*1/6+1/8*1/10+1/8*1/15+1/8*1/21)*56

=(1+1/3+1/6+1/10+1/15+1/21)*1/8*56

=(1+1/2+1/6+1/21)*7

=(5/3+1/21)*7

=36/21*7

=12

3.(7-11/16*3)+(1-11/16*7)+(5-11/16)+(3-11/16*5)

=7+1+5+3-11/16*3-11/16*7-11/16-11/16*5

=16-(3+7+1+5)*11/16

=16-16*11/16

=5

这几个题主要考察了混合运算的分配法 呵呵