Đáp án:
Bài 1 : Tính ( hợp lý nếu có thể )
a, ( - 12 ) . 3 - 5 . ( - 7 )
= [ ( -12 ) . 5 ] . [ ( - 7 ) - 5 ]
= [ ( - 60 ) . ( - 15 ) ]
= 720
b, ( - 8 - 2 ) . ( - 3 ) + 5 . ( - 12 )
= - 8 - 2 . ( - 3 ) + 5 . ( - 12 )
= ( - 8 ) + ( - 2 ) . ( - 3 ) + 5 . ( - 12 )
= [ ( - 2 ) + ( - 8 ) ] . [ ( - 12 ) . 5 ] + ( - 3 )
= ( - 10 ) . ( - 60 ) + ( - 3 )
= [ ( - 10 ) . ( - 60 ) ]
= 600. + ( - 3 )
= 597
c, [ ( - 9 ) - ( - 7 ) ] . ( - 5 ) - 15 . ( - 3 )
= [ ( - 9 ) + ( - 7 ) ] . ( - 5 ) - 15 . ( - 3 )
= ( - 17 ) . [ ( - 5 ) - 15 ] . ( - 3 )
= ( - 17 ) . ( - 20 ) . ( - 3 )
= [ ( - 17 ) . ( - 20 ) ] . ( - 3 )
= 340 . ( - 3 )
= - 1020
d, - 12 . 25 + 38 . ( - 12 ) - 12 . 37
= ( - 12 ) . 25 + 38 . ( - 12 ) + ( - 12 ) . 37
= ( -12 ) . ( 25 + 38 + 37 )
= ( - 12 ) . 100
= [ ( - 12 ) . 100 ]
= - 1200
e, - 28 . 35 - 100 . 65 + 35 . ( - 72 )
= ( - 28 ) . 35 + ( - 100 ) . 65 + 35 . ( - 72 )
= [ ( - 28 ) . 35 ] + ( - 100 ) . 65 + 35 . ( - 72)
= (- 980 ) + [ (- 100 ) . 65 ] + 35 . ( -72 )
= ( - 980 ) + ( - 6500 ) + [ 35 . ( -72 ) ]
= ( - 980 ) + ( - 6500 ) + ( - 2520 )
= [ ( - 980 ) + ( - 6500 ) ] + ( - 2520 )
= ( - 7480 ) + (- 2520 )
= [ ( - 7480 ) + ( - 2520 )]
= - 10000
g, 124.( -15 )- 15 . ( - 24 )+ 2. ( - 25 )
= [ 124 . ( - 15 ) ] - 15 . ( - 24 ) + 2 . ( - 25 )
= (- 1860 ) - 15 . ( - 24 )+ 2 . ( - 25 )
= ( - 1860 ) + ( - 15 ) . ( - 24 ) + 2 . ( - 25 )
= ( - 1860 ) + [ ( - 15 ) . ( - 24 ) ] + 2 . ( - 25 )
= ( - 1860 ) + 360 + 2 . ( - 25 )
= ( - 1860 ) + 360 + [ 2 . ( - 25 ) ]
= ( - 1860 ) + 360 + ( - 50 )
= [ ( -1860 ) + 360 ] + ( - 50 )
= ( - 1500 ) + ( - 50 )
= [ ( - 1500 ) + ( - 50 ) ]
= 75000
h, 12.( 34 - 27 ) - 34 . ( 12 - 27 )
= 12 . 34 + ( - 27 ) + ( - 34 ) . 12 + ( - 27 )
= [ ( - 34 ) + 34 ] + [ ( - 27 ) + 27 ] . 12 . 12
= 0. + 0 . 12 .12
= 0 . 12 . 12
= 0 . 144
= 0
i, ( - 2 ) mũ 3 . 24 - 12 . 2 mũ 3 . 3
= [ ( - 2 ) mũ 3 . 24 ] +( - 12 ) . 2 mũ 3 . 3
= 192. + [ ( - 12 ) . 2 mau 3 ] . 3
= 193 + ( - 96 ) . 3
= 193 + [ ( - 96 ) . 3 ]
= 193 + ( - 288 )
= [ 193 + ( - 288 ) ]
= - 95
k, 25 . ( - 3 )mũ 2 + 75 . 9
= [ 25 . ( - 3 )mũ 2 ] + 75 .9
= ( - 255 ) + 75 . 9
= ( - 255 ) + ( 75 . 9 )
= ( - 255 ) + 675
= 420
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