初一数学题(加法运算律在加减混合运算中的作用)
1个回答

(+1/2)-[(-2) +( 1/2)]

=1/2-(-2+1/2)

=1/2+2-1/2

=2

-3-4+19-11+2

=-3-4+8+2

=-7+10

=3

-4.2+5.7-7.6+10.1-5.5

=1.5-7.6+10.1-5.5

=-4-7.6+10.1

=-1.5

(-52)+(-19)-(+37)-(-24)

=-52-19-37+24

=-(52+19+37)+24

=-84

13-[26-(-21)+(-18)]

=13-(26+21-18)

=13-29

=-16

丨-9/4丨-(-3/4)+1-丨1-1/2丨

=9/4+3/4+1-1/2

=3+1-1/2

=7/2