1.42 Tính hợp lí : a) 5.11.18+9.31.10+4.29.45 b)37.39+78.14+13.85+52.55 06/07/2021 Bởi Daisy 1.42 Tính hợp lí : a) 5.11.18+9.31.10+4.29.45 b)37.39+78.14+13.85+52.55
`a, 5 . 11 . 18 + 9 . 31 . 10 + 4 . 29 . 45` `= 5 . 11 . 2 . 9 + 90 . 31 + 2 . 2 . 29 . 5 . 9` `= 90 . 11 + 90 . 31 + 90 . 48` `= 90 . ( 11 + 31 + 48 )` `= 90 . 90` `= 8100` `b, 37 . 39 + 78 . 14 + 13 . 85 + 52 . 55` `= 37 . 39 + 39 . 2 . 14 + 13 . 5 . 17 + 13 . 4 . 5 . 11` `= 37 . 39 + 39 . 28 + 65 . 17 + 65 . 44` `= 39 . ( 37 + 28 ) + 65 . ( 17 + 44 )` `= 39 . 65 + 65 . 61` `= 65 . ( 39 + 61 )` `= 65 . 100` `= 6500` Bình luận
Đáp án: `a) \ \ 9000` `b) \ \ 6500` Giải thích các bước giải: `a)` `5.11.18+9.31.10+4.29.45` `=90.11+90.31+2.29.90` `=90.(11+31+2.29)` `=90.100=9000` `b)` `37.39+78.14+13.85+52.55` `=37.39+39.2.14+13.5.17+13.4.5.11` `=39.(37+2.14)+65.17+65.44` `=39.65+65.(17+44)` `=39.65+65.61` `=65.(39+61)` `=65.100=6500` Bình luận
`a, 5 . 11 . 18 + 9 . 31 . 10 + 4 . 29 . 45`
`= 5 . 11 . 2 . 9 + 90 . 31 + 2 . 2 . 29 . 5 . 9`
`= 90 . 11 + 90 . 31 + 90 . 48`
`= 90 . ( 11 + 31 + 48 )`
`= 90 . 90`
`= 8100`
`b, 37 . 39 + 78 . 14 + 13 . 85 + 52 . 55`
`= 37 . 39 + 39 . 2 . 14 + 13 . 5 . 17 + 13 . 4 . 5 . 11`
`= 37 . 39 + 39 . 28 + 65 . 17 + 65 . 44`
`= 39 . ( 37 + 28 ) + 65 . ( 17 + 44 )`
`= 39 . 65 + 65 . 61`
`= 65 . ( 39 + 61 )`
`= 65 . 100`
`= 6500`
Đáp án:
`a) \ \ 9000`
`b) \ \ 6500`
Giải thích các bước giải:
`a)`
`5.11.18+9.31.10+4.29.45`
`=90.11+90.31+2.29.90`
`=90.(11+31+2.29)`
`=90.100=9000`
`b)`
`37.39+78.14+13.85+52.55`
`=37.39+39.2.14+13.5.17+13.4.5.11`
`=39.(37+2.14)+65.17+65.44`
`=39.65+65.(17+44)`
`=39.65+65.61`
`=65.(39+61)`
`=65.100=6500`