三道七年级的数学题有哪位知道

来源:百度知道 编辑:UC知道 时间:2024/07/03 12:39:55
(1) (+2\5)-(-3\5)
(2) (-2\5)-(-3\5)
(3) (-1\2)-1\3

(1)+1
(2)+1/5
(3)-5/6

快乐鼠尾草123,(1) (+2\5)-(-3\5) =2\5+3\5=1
(2) (-2\5)-(-3\5) =-2\5+3\5=1\5
(3) (-1\2)-1\3=-(1\2+1\3)=-5\6

(1)(+2÷5)-(-3÷5) (2)(-2÷5)-(-3÷5)
=[2-(-3)]÷5 =[-2-(-3)]÷5
=5÷5 =1÷5
=1 =1/5
(3)(-1÷2)-1÷3
=-1/2-1/3
=-1/2+(-1/3)
=-5/6

(1)=2/5+3/5
=1
(2)=-2/5+3/5
=1/5
(3)=-1/2-1/3
=-3/6-2/6
=-5/6

=1
=0.2
=5/6

(+2/5)-(-3/5)
解:原式=2/5+3/5
=1

(-2/5)-(-3/5)
解:原式=(-2/5)+3/5
=3/5-2/5
=1/5

(-1/2)-1/3
解:原式=-(1/2+1/3)
=-5/6