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 ,
By Valentina
Đáp án
`a ) 1975 . ( – 115 ) + 1979 . 5`
`=1975.(-23).5+1979.5`
`=5(-45425+1979)`
`=5.(-43446)`
`=-217230`
`b) 153 . 171 – 153 . 77`
`=153(171-77)`
`=153.94`
`=14382`
`c)199 . ( 15 . 17 ) – 199 . ( – 17 + 5 )`
`=199.255-199.(-12)`
`=199.(255–12)`
`=199.267`
`=53133`
`d)-39 ( 5 – 99) + 99 ( 10 – 39 )`
`=(-39).5-(-39).99+99.10-99.39`
`=-39.5+39.99+99.10-99.39`
`=-39.5+99.10`
`=-39.5+99.2.5`
`=5(-39+99.2)`
`=5.159`
`=795`
`d)- 8 : ( -2 ) – 2 . ( – 10 : 2 ) – 7 ( 5 – 4 )`
`=4-2.(-5)-7.1`
`=4+10-7`
`=7`
`f)7 . [ – 6 : 2 – 15 : ( – 3 ) ] – | – 3 |`
`=7.[-3+5]-3`
`=7.2-3`
`=14-3=11`
Đáp án:
Giải thích các bước giải:
`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)`
`=59700-6567`
`=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`