tính hợp lí
a , 1975 . ( – 115 ) + 1979 . 5
b , 153 . 171 – 153 . 77
c , 199 . ( 15 . 17 ) – 199 . ( – 17 + 5 )
d , -39 ( 5 – 99) + 99 ( 10 – 39 )
e , – 8 : ( -2 ) – 2 . ( – 10 : 2 ) – 7 ( 5 – 4 )
f , 7 . [ – 6 : 2 – 15 : ( – 3 ) ] – | – 3 |
tính hợp lí
a , 1975 . ( – 115 ) + 1979 . 5
b , 153 . 171 – 153 . 77
c , 199 . ( 15 . 17 ) – 199 . ( – 17 + 5 )
d , -39 ( 5 – 99) + 99 ( 10 – 39 )
e , – 8 : ( -2 ) – 2 . ( – 10 : 2 ) – 7 ( 5 – 4 )
f , 7 . [ – 6 : 2 – 15 : ( – 3 ) ] – | – 3 |
Đáp án:
Giải thích các bước giải:
a/. 1975 . ( – 115 ) + 1979 . 5
= 1975 . ( – 23 ) .5 + 1979 . 5
= 5. (1975 . -23 + 1979)
= 5.( -45 425 + 1979)
= 5 . (-43 446)
= – 217 230
b/. 153 . 171 – 153 . 77
= 153.(171 – 77)
= 153 . 94
= 14 382
c/. 199 . ( 15 . 17 ) – 199 . ( – 17 + 5 )
= 199 . 255 – 199 . (-12)
= 199.[255 – (-12)}
= 199 . 267
= 53 133
d/. -39 ( 5 – 99) + 99 ( 10 – 39 )
= -39 . 5 + 39 . 99 + 99.10 – 99 . 39
= (39 . 99 – 99 . 39) + (99.10 – 39 .5)
= 39.(99 -99) + (99.2.5 – 39 .5)
= 0 + 5.(99.2 – 39)
= 5. 159
= 795
e/. – 8 : ( -2 ) – 2 . ( – 10 : 2 ) – 7 ( 5 – 4 )
= 4 – 2. (-5) – 7. 1
= 4 + 10 – 7
= 14 – 7
= 7
f/. 7 . [ – 6 : 2 – 15 : ( – 3 ) ] – | – 3 |
= 7 . [ (- 6 : 2) – 15 : ( – 3 ) ] – 3
= 7. [ -3 – (-5) ] – 3
= 7. 2 – 3
= 14 – 3
= 11
@py
`\text{Mong bạn cho mình ctlhn ạ!!!}`
`a)1975. ( − 115) + 1979. 5`
`= 1975. ( − 115) + (1975 + 4).5`
`= 1975. ( − 115) + 1975.5 + 4.5`
`= 1975. ( − 115 + 5) + 20`
`= 1975. ( − 110) + 20`
`= − 217250 + 20 `
`= − 217230`
`b)153. 171 − 153. 77`
`= 153. (171 − 77)`
`= 153.94`
=` 153. (100 − 6)`
`= 153.100 − 153.6`
`= 15300 − 918 `
`= 14382`
`c)199. (15. 17) − 199. ( − 17 + 5)`
`= 199.255 − 199. ( − 12)`
`=199.255 + 199.12`
`= 199. (255 + 12)`
=` 199.267`
`= 199. (300 − 33)`
`= 53133`
`d) − 39(5 − 99) + 99(10 − 39)`
`= − 39.5 + 39.99 + 99.10 − 39.99`
`= − 39.5 + 99.10`
`= − 39.5 + 99.5.2`
`= − 39.5 + 198.5`
`= ( − 39 + 198).5`
`= 159.5`
`= 795`
`e) − 8: ( − 2) − 2. ( − 10: 2) − 7(5 − 4)`
`= 4 − 2. ( − 5) − 7.5 + 7.4`
`= 4 + 10 − 35 + 28`
`=7`
`f)7. [ − 6: 2 − 15: ( − 3)] − | − 3|`
`= 7. [ − 3 + 5] − 3`
`= 7.2 − 3 = 14 − 3 `
`= 11`