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
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Ta có: \(13\cdot\left(-47\right)-53\cdot13\)
\(=13\cdot\left(-47-53\right)\)
\(=13\cdot\left(-100\right)=-1300\)
Ta có: \(27\cdot\left(-67\right)+33\cdot\left(-27\right)\)
\(=27\cdot\left(-67\right)-33\cdot27\)
\(=27\left(-67-33\right)\)
\(=27\cdot\left(-100\right)=-2700\)
Ta có: \(-49\cdot65+36\cdot\left(-49\right)+49\)
\(=-49\cdot65+\left(-49\right)\cdot36+\left(-49\right)\cdot\left(-1\right)\)
\(=-49\cdot\left(65+36-1\right)\)
\(=-49\cdot100=-4900\)
Ta có: \(136\cdot\left(-47\right)+36\cdot47\)
\(=\left(-136\right)\cdot47+36\cdot47\)
\(=47\cdot\left(-136+36\right)\)
\(=47\cdot\left(-100\right)=-4700\)
Ta có: \(\left(-48\right)\cdot72+36\cdot\left(-304\right)\)
\(=-96\cdot36+36\cdot\left(-304\right)\)
\(=36\cdot\left(-96-304\right)\)
\(=36\cdot\left(-400\right)=-14400\)
a, 53 x 39 + 47 x 39 - 53 x 21 - 47 x 21
= 53 x (39-21) + 47 x (93-21)
=53 x 18 + 47 x 18
= (53 +47) x 18
=100 x 18
=1800
b,2 x 53 x 12 + 4 x 6 x 87 - 3 x 8 x 40
=24 x 53 + 24 x 87 - 24 x 40
=24 x (53+87-40)
=24 x 100
=2400
c,5 x 7 x 77 - 7 x 60 +49 x 25 -15 x 42.
=5 x 7 x 77 - 7 x 5 x 12 +49 x 5 x 5 - 5 x 3 x 42.
=5 x 539 - 84 x 5 +245 x 5 -5 x 126
=5 x (539 - 84 +245 -126)
=5 x 574
=2870
a, 53 * 39 + 47 * 59 - 53 * 21 - 47 * 21 c, (43 * 52 - 43 ) : ( 4 * 42 )
= ( 53 + 47 ) * 39 - ( 53 + 47 ) * 21 = ( 64 * 25 - 64 ) : ( 4 * 16 )
= 100 * 39 - 100 * 21 = ( 1600 - 64 ) : 64
= ( 39 - 21 ) * 100 = 1536 : 64
= 18 * 100 = 24
= 1800
`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`
X=(1800+600):30):560:(315:35)
X=(2400:30):560:9
X=80:560:9
X=80x1/560x1/9
X=1/7x1/9
X=1/63
A=58x72+63x81-58x52-63x61
= (58x72-58x52)+(63x81-63x61)
= 58(72-52)+63(81-61)
= 58x20+63x20
= 1160+1260
= 2420
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`