Đáp án+Giải thích các bước giải:
Bài `2:`
`a) 75 . 20,9 + 5^2 . 20,9`
`= 75 . 20,9 + 25 . 20,9`
`=20,9 .(75+25)`
`=20,9 .100`
`=2090`
`b) 86.15 + 150 . 1,4`
`= 86.15 + 15.10 . 1,4`
`=86 . 15 + 15 . 14`
`=15.(86+14)`
`=15 . 100`
`=1500`
`c) 93.32+14.16`
`=93.32+7.2.16`
`=93.32+7.32`
`=32.(93+7)`
`=32 . 100`
`=3200`
`d) 98,6 .199 - 990 . 9,86`
`= 98,6 .199 - 99.10 . 9,86`
`=98,6 .199 - 99 . 98,6`
`=98,6 . (199-99)`
`= 98,6 .100`
`= 9860`
`e) -8.40+2.108 + 24`
`= -8 . 40 + 2 . 4 . 27 + 8 .4`
`=-8. 40 -8.(-27) - 8.(-3)`
`= -8. (40 - 27-3)`
`=-8 . 10`
`=-80`
`f) 993 . 98 + 21 . 331 - 50 . 99,3`
`=993 . 98 + 7.3.331 - 5 . 10 . 99,3`
`=993 . 98 + 7 . 993 - 5. 993`
`=993 .(98+7-5)`
`=993 . 100`
`=99300`
