a) 10-15+20-25+….+100-105
b) 1-3+5-7+…+201-203
c) (723-38)-723
d) -1982-(18-1982)
e) (2017-82+17)-(-82+2017)
f) -(-79+18)+(-18-79+6)
TRÌNH BÀY ĐẦY ĐỦ MÌNH SẼ VOTE 5* UY TÍN TẠO NÊN THƯƠNG HIỆU
a) 10-15+20-25+….+100-105
b) 1-3+5-7+…+201-203
c) (723-38)-723
d) -1982-(18-1982)
e) (2017-82+17)-(-82+2017)
f) -(-79+18)+(-18-79+6)
TRÌNH BÀY ĐẦY ĐỦ MÌNH SẼ VOTE 5* UY TÍN TẠO NÊN THƯƠNG HIỆU
a) 10 – 15 + 20 – 25 + … + 100 – 105
10 – 15 + 20 – 25 + … + 100 – 105
= (10 – 15) + (20 – 25) + … + (100 – 105) (có 20 : 2 = 10 ngoặc)
= -5 . 10
= -50
b) 1 – 3 + 5 – 7 + … + 201 – 203
= (1 – 3) + (5 – 7) + … + (201 – 203) (có 102 : 2 = 51 ngoặc)
= -2 . 51
= -102
c) (723 – 38) – 723
= 723 – 38 – 723
= (723 – 723) – 38
= 0 – 38
= -38
d) -1982 – (18 – 1982)
= -1982 – 18 + 1982
= (-1982 + 1982) – 18
= 0 – 18
= -18
e) (2017 – 82 + 17) – (-82 + 2017)
= 2017 – 82 + 17 + 82 – 2017
= (2017 – 2017) + (82 – 82) + 17
= 0 + 0 + 17
= 17
f) -(-79 + 18) + (-18 – 79 + 6)
= 79 – 18 – 18 – 79 + 6
= (79 – 79) + (-18 – 18) + 6
= 0 + -36 + 6
= -30
`text{a) 10 – 15 + 20 – 25 + … + 100 – 105}`
`text{10 – 15 + 20 – 25 + … + 100 – 105}`
`text{= (10 – 15) + (20 – 25) + … + (100 – 105) (có 20 : 2 = 10 ngoặc)}`
`text{= -5 . 10}`
`text{= -50}`
`text{b) 1 – 3 + 5 – 7 + … + 201 – 203}`
`text{= (1 – 3) + (5 – 7) + … + (201 – 203) (có 102 : 2 = 51 ngoặc)}`
`text{= -2 . 51}`
`text{= -102}`
`text{c) (723 – 38) – 723}`
`text{= 723 – 38 – 723}`
`text{= (723 – 723) – 38}`
`text{= 0 – 38}`
`text{= -38}`
`text{d) -1982 – (18 – 1982)}`
`text{= -1982 – 18 + 1982}`
`text{= (-1982 + 1982) – 18}`
`text{= 0 – 18}`
`text{= -18}`
`text{e) (2017 – 82 + 17) – (-82 + 2017)}`
`text{= 2017 – 82 + 17 + 82 – 2017}`
`text{= (2017 – 2017) + (82 – 82) + 17}`
`text{= 0 + 0 + 17}`
`text{= 17}`
`text{f) -(-79 + 18) + (-18 – 79 + 6)}`
`text{= 79 – 18 – 18 – 79 + 6}`
`text{= (79 – 79) + (-18 – 18) + 6}`
`text{= 0 + -36 + 6}`
`text{= -30}`