Tính bằng cách thuận tiện: a) 35 .18 – 5 . 7 . 28 b) 45 – 5 . (12 + 9) c) 24 . (16 – 5) – 16 . (24 - 5) d) 29 . (19 – 13) – 19 . (29 – 13)
2 câu trả lời
`a)35 .18 – 5 . 7 . 28`
`= 35.18 - 35.28`
`= 35.(18-28)`
`=35.(-10)`
`= -350`
`b)45 – 5 . (12 + 9)`
`=45 - 5.12 -5.9`
`=45 - 60 -45`
`=-60`
`c) 24 . (16 – 5) – 16 . (24 - 5)`
`=24.16 - 24.5 -16.24 + 16.5`
`=-120 + 80`
`=-40`
`d)29 . (19 – 13) – 19 . (29 – 13)`
`= 29.19 - 13.29 - 19.29 + 19.13`
`=13.(-29 + 19)`
`=13.(-10)`
`=-130`
Tính bằng cách thuận tiện :
a) `35 . 18 - 5 . 7 . 28`
`= 35 . 18 - ( 5 . 7 ) . 28`
`= 35 . 18 - 35 . 28`
`= 35.(18-28)`
`=35.(-10)`
`=-350`
b) `45 - 5 . ( 12 + 9 )`
`=45-5.12-5.9`
`=45-60-45`
`=45-45-60`
`=0-60`
`=-60`
c) `24 . ( 16 - 5 ) - 16 .( 24 -5 )`
`=24 . 16 - 24.5 - 16. 24 - 16.5`
`=-120+80`
`=-40`
d) `29.(19-13)-19.(29-13)`
`=29.19-29.13-19.29-13`
`=13.(-29+19)`
`=13.(-10)`
`=-130`