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a,=3/13.17/29.29/34
=3/13.1/2
=3/26
b,=(4/21+25/42).19/33
=11/14.19/33
=19/42
`a, = 3/13 xx (17/29 xx 29/34)`
`= 3/13 xx 1/2`
`= 3/26`.
`b, = 19/33(4/21 + 25/42)`
`= 19/33 xx ( 33/42 )`
`= 19/42`
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d) 12x 156 - 12 x 55 - 12
= 12 x ( 156 - 55 - 12 )
= 12 x 100
= 1200
e ) 12 x 11 + 21 x 11 + 11 x 33
= ( 12+ 21 + 33) x 12
= 66 x 11
= 726
g) 132 x 11 - 11 x 32 - 54 x 11
= ( 132 - 32 - 54 ) x 11
= 46 x 11
= 506
d) 12 x 156 - 12 x 55 - 12 = 12x(156 - 55 - 1 ) = 12 x 100 = 1200
e) 12 x 11 + 21 x 11 + 11 x 33 = 11 x ( 12 + 21 + 33 ) = 11 x 66 = 726
g) 132 x 11 - 11 x 32 - 54 x 11 = 11 x ( 132 - 32 - 54 ) = 11 x 46 = 506
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Hướng dẫn giải:
a) x < 5 : x = 0, 1, 2, 3, 4.
b) x là số tròn trăm vào 680 < x < 790 : x = 700.
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\(141\cdot25+216109\cdot3\)
\(=3\cdot47\cdot25+216109\cdot3\)
\(=3\left(47\cdot25+216109\right)\)
\(=3\cdot217284=651852\)
\(523790-305\cdot26\cdot3\)
\(=2\cdot5\cdot52379-2\cdot5\cdot13\cdot61\cdot3\)
\(=10\left(52379-13\cdot61\cdot3\right)\)
\(=10\cdot50000=500000\)
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a)12 x 11 + 21 x 11 x 11 + 11 x 33
= ( 12 x 11 ) + ( 21 x 11 x 11 ) + ( 11 x 33 )
= 132+2541+363132+2541+363
= 30363036
b)132x11-11x32-54x11
= ( 132 x 11 ) - ( 11 x 32 ) - ( 54 x 11 )
=1452−352−594=1452−352−594
= 506506
\(a,=11\times\left(12+21+33\right)=11\times66=726\\ b,=11\times\left(132-32-54\right)=11\times46=506\\ c,=11\times\left(245+365\right)=11\times610=6710\\ d,=75\times\left(78+89+123\right)=75\times290=21750\\ e,=\left(2\times50\right)\times\left(250\times8\right)=100\times2000=200000\\ g,=1994\times\left(867+11\right)=1994\times878=1750732\)
33 . x + 29 . x + 54 . x = 790
x( 33 + 29 + 54 ) = 790
x . 116 = 790
x = 790/116 = 395/58