Bài làm

a) ( -85 ) . 35 - 85 . 65 - ( - 10 )² 

= ( -85 ) . 35 - 85 . 65 + 100

= -85( 35 + 65 ) + 100
= -85 . ( 100 ) + 100

= -8500 + 100

= -8400

b) -88 . 57 - 88 . 42 - 88

= -88 ( 57 + 42 + 1 )

= -88 . 100

= -8800

# Học tốt #

Cảm ơn bạn tốt nha

a, -(-15+125-81)-(-85+75-19+100)

=-15-125+81-(-85)-75+19-100

=-140+81-(-85)-75+19-100

=-59-(-85)-75+19-100

=-16-75+19-100

=-91+19-100

=-72-100

=-172

Khiếp

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

\(27.332+93.43+57.61+69.57\\ =27.332+93.43+57.\left(61+69\right)\\ =27.332+93.43+57.130\\ =8964+3999+7410=20373\\ 34.75+75.66-65.100\\ =\left(34+66\right).75-65.100\\ =100.75-65.100\\ =100.\left(75-65\right)\\ =100.10=1000\\ \left(456.11+912\right).37:13:74\\ =5928:13:\left(74:37\right)\\ =456:2=228\\ 6^2:4.3+2.5^2\\ =36:4.3+2.25\\ =9.3+50=27+50=77\\ 5.4^2-18:3^2\\ =5.16-18:9\\ =80-2=78\\\left[\left(315+372\right).3+\left(372+315\right).7\right]:\left(26.13+74.14\right)\\ =687.\left(3+7\right):\left(338+1036\right)\\ 687.10:1374\\ =6870:1374=5\\ 12:\left\{390:\left[500-\left(125+35.7\right)\right]\right\}\\ =12:\left[390:\left(500-370\right)\right]\\ =12:\left(390:130\right)=12:3=4\\ 192000-\left(1500.2+1800.3+1800.2:3\right)\\ =192000-\left(3000+5400+1200\right)\\ =192000-9600=182400\)

ai nhanh mình k nha . mình đang cần gấp

[(65-1):4+1].(65+1):2=561

49-51+53-55+57-59+61-63+65=57

                chúc bạn học tốt

                               ^^

49-51+53-55+57-59+61-63+65 
=(49+-51)+(53+-55)+(57+-59)+(61+-63)+65
=-2+-2+-2+-2+65
=-8+65
=57
Nhớ k cho mình nha mệt lắm đó 

nh tong cua B= 49 – 51 + 53 – 55 + 57 – 59 + 61 – 63 + 65 
B = 49 + (53 - 51) + ( 57 - 55) + (61 - 59) + ( 65 - 63) áp dụng giao hoán và kết hợp 
B = 49 + 2 + 2 + 2 + 2 = 57

49-51+53-55+57-59+61-63+65

= (49-59) + ( -51+61) + (53-63) + (-55+65) +57

= (-10) + 10 + (-10) +10 +57

= 0 +0 +57

=57

a ,      35 * 34 + 35 * 86 + 65 * 75 + 65 * 45 

=   35 * ( 34 + 86 ) + 65 * (75 + 45 )

= 35 * 120 + 65 * 120

= 120 * ( 35 + 65 )

= 120 * 100

= 12000

b , 11+12 + ...+ 20

= ( 11 +19 ) +( 12 + 18 ) + ( 13 + 17 ) + ( 14 + 16 ) +15 +20

= 30 + 30 + 30 + 30 + 15 + 20 

= 30 * 4 + 35

= 120 + 35

= 155

c , 8 * 9 * 11 + 6 * 20 * 12 + 19 * 4 * 18

= 792 + 1440 + 1368

=3600

d , 143 * ( 57 - 36 ) - 57 * ( 143 - 36 )

= 143 * 57 - 143 * 36 - 57 * 143 - 57 * 36

= 143 * 57 - 57 * 143 - 143  * 36 - 57 * 36

= 0 - ( 143 - 57 )

= 0 - 86 

= - 86

a) \(35.34+35.86+65.75+65.45\)

\(=35.\left(34+86\right)+65.\left(75+45\right)\)

\(=35.120+65.120\)

\(=\left(35+65\right).120\)

\(=100.120\)

\(=12000\)

b) \(11+12+...+20\)

Số số hạng của dãy là : (20 - 11) : 1 + 1 = 10 (số)

Tổng của dãy là : (20 + 1) x 10 : 2 = 105

c) \(8.9.11+6.20.12+19.4.18\)

\(=\left(8.9\right).11+\left(6.12\right).20+\left(4.18\right).19\)

\(=72.11+72.20+72.19\)

\(=72.\left(11+20+19\right)\)

\(=72.50\)

\(=3600\)

d) \(143.\left(57-36\right)-57.\left(143-36\right)\)

\(=143.57-143.36-57.143-57.36\)

\(=\left(143.57-57.143\right)-\left(143.36-57.36\right)\)

\(=0-36.\left(143-57\right)\)

\(=0-36.86\)

\(=0-3096\)

\(=-3096\)

_Chúc bạn học tốt_

=77(5x7+65)-21x57-21x43

=77x100-(21x57+21x43)

=7700-21(57+43)

=7700-21.100

=7700-2100

=5600