18-3.x2=57
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=1/1-1/2+1/2 -1/3+1/3-1/4....... 1/56 -1/57+1/57-1/58
= 1/1-1/58
= 57/58
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\(\left[57+3\left(x-10\right)\right]:18=9=>57+3\left(x-10\right)=9.18=162\)
\(=>3\left(x-10\right)=162-57=105=>x-10=105:3=35=>x=35+10=45\)
\(\left(57+3\left(x-10\right)\right):18=9\)
\(=>57+3\left(x-10\right)=162\)
\(=>3\left(x-10\right)=105\)
\(=>x-10=35\)
\(=>x=45\)
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a)
9 8 − 4 7 + − 1 8 + 11 7 = 9 8 + − 1 8 + − 4 7 + 11 7 = 1 + 1 = 2
b)
− 5 7 ⋅ 3 11 + − 5 7 ⋅ 8 11 + 5 7 = − 5 7 3 11 + 8 11 − 1 = − 5 7 .0 = 0
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a,
73.( 8 - 59 ) - 59.( 8 - 73 )
=73.8 -73. 59 - 59.8 - 73.59
=8(73-59)-73(59-59)
=8.14-0
=112
b,Tương tự câu a
c,Tương tự câu a
a) 73 . ( 8 - 59 ) - 59 . ( 8 - 73) b) 159 . ( 18 - 59 ) - 59. ( 18 - 159 ) c) - 145 . ( 13 - 57 ) + 57. ( 10 - 145 )
= 73 . 8 - 73 . 59 - 59 .8 - 59 .73 = 159 . 18 - 159 . 59 - 59 . 18 - 59 . 159 = ( - 145 ) . 13 - (- 145) . 57 + 57 . 10 -57.145
= 8 . ( 72 - 59 ) - 73 . ( 59 - 59 ) = 18 . (159 - 59 ) - ( 59 - 59) - ( 159 - 159) =(-145).13-(-145).57+57.(10-145)
= 8 . 14 - 0 = 1800 - 0 - 0 = (-145).13- (-145).57 + (-135)
= 112 = 1800 = -145.(13 - 57) + (-135)
=6380 + (-135 )
=6245
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2 . 53 . 27 + 6 . 9 . 87 - 3 . 18 . 40
= 2. 53 . 9 . 3 + 2. 3 .9 .87 - 3 .2 .9 .40
= 54.53+54.87-54.40
=54(53+87-40)
=54. 100=5400
12 . 25 + 29 . 25 + 59 . 25
= 25 . ( 12+29+59)
=25 . 90
=2250
43 . 37 + 93 . 43 + 57 . 61 + 69 . 57
= 43.(37+93)+57(61+69)
=43.130+57.130
=130.(43+57)
=130.100
=13 000
12 . 53 + 53 . 172 - 53
=53(12+172-1)
=53.184
=9752
35 . 54 + 35 . 58 + 65 . 75 + 65 . 45
=35(54+58)+65(75+45)
=35.112+65.120
=3920+7800
=11720
39 . 8 + 70 . 3 + 31 . 8
=8(39+31)+70.3
=8.70+70.3
=70.(8+3)
=70.11
=770
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