57:49:39+49-13=?
Do làm duoc
Tính các tổng sau một cách hợp lí:
a ) 1 2 + − 2 4 + 4 8 ; b ) − 3 9 + 16 40 + − 8 12 + 2 10 ; c ) − 1 8 + 6 7 + 2 14 + − 7 8 + 7 9 ; d ) 1 2 + − 1 5 + − 5 7 + 1 6 + − 3 35 + 1 3 e ) − 1 2 + 1 3 + − 1 4 + − 2 8 + 4 18 + 4 9
a ) 1 2 . b ) − 2 5 . c ) − 7 8 . d ) 0. e ) 0.
(367-24)-367
(17-600)+23
-2016 -(12-20160
(18 - 29)- (24+18-29)
-(13+49)+(13-100+49)
-23+(100-57)
a, (367-24)-367=343-367
=(-24)
b,(17-600)+23=-583+23
=(-560)
c,-2016-(12-2016)=-2016-(-2004)
=(-2016)+2004
=(-12)
d, (18-29)-(24+18-29)=(-11)-13
=(-24)
e, -(13+49)+(13-100+49)=(-62)+(-38)
=-100
f, -23+(100-57)=(-23)+43
=20
Thực hiện phép tính :
a) 123 - 27 + 27 + 13 - 123
b) 175 + 25 + 13 + 15 - 175 - 25
c) 53 x 39 + 47 x 39 + 53 x 21 + 47 x 21
d) 49 x 35 + 49 x 16 - 49 x 61
a) `123 - 27 + 27 + 13 - 123`
`= (123 - 123) + (27 - 27) + 13`
`= 0 + 0 + 13`
`= 13`
`---`
b) `175 + 25 + 13 + 15 - 175 - 25`
`= (175-175)+(25-25)+25+13`
`=0+0+25+13`
`=28`
`---`
c) \(53\times39+47\times39+53\times21+47\times21\)
\(=\text{[}\left(53+47\right)\times39]+\left[\left(53+47\right)\times21\right]\)
\(=\left(100\times39\right)+\left(100\times21\right)\)
\(=3900+2100\)
`=6000`
`---`
d) \(49\times35+49\times16-49\times61\)
`=` \(49\times\left(35+16-61\right)\)
`=` \(49\times\left(-10\right)\)
`=-490`
Tính bằng cách hợp lí:
16/27 x 13/29 + 16/27 x 14/ 29
48/49 + 15/39 - 18/49 + 15/39
`16/27xx13/29+16/27xx14/29`
`=16/27xx(13/29+14/29)`
`=16/27xx27/29`
`=16/29`
`48/49+15/39-18/49+15/39`
`=(48/49-18/49)+(15/39+15/39)`
`=30/49+30/39`
`=880/637`
tính nhanh : (57 - 28 + 49) - (49 + 57)
\(=57-28+49-49-57\\ =\left(57-57\right)+\left(49-49\right)-28=0+0-28=-28\)
57.(49-16)-57.(24+49=????
57.(49-16)-57.(24+49)=?
57 . 33 - 57 . 73
= 57 . ( 33 - 73 )
= 57 . (-40)
= -2280
Học Tốt !
Trl :
57.(49-16)-57.(24+49= - 2280
Học tốt !
57(49-16)-57.(24+49)
=57.49-57.16-57.24-57.49
=(57.49-57.49)-(57.16+57.24)
=0-57.(16+24)
=0-57.40
=0-2280
=-2280
Tinh
D=57.(49-19)-57.(24+49)
D=57.(49-19)-57.(24+49)
<=>D=57.30-57.73
<=>D=57.(30-73)
<=>D=57.(-43)
<=>D=-2451
D=57.(49-19)-57.(24+49)
=57.(49-19-24-49)
=57.(-33)
=1881
Học tốt!
co 49 lit dau duoc dung trong 7 thung trong do co mot can to hon dung 13 lit .cac hung con lai chua so dau bang nhau.hoi moi thung con lai chua bao nhieu lit dau?
moi thung con lai co so l dau la:
<49-13>÷<7-1>=6<l dau>
d/s:6l dau
Tìm x, biết:
a ) 2 5 . x + 1 3 = 1 5 b ) 4 9 − 5 3 . x = − 2 c ) 1 5 + 5 3 : x = 1 2 d ) 5 7 : x − 3 = − 2 7