\(35\cdot\left(115-57\right)-115\cdot\left(35-57\right)\)

\(=35\cdot115-35\cdot57-115\cdot35+115\cdot57\)

\(=\) \(-35\cdot57+115\cdot57\)

\(=57\cdot\left(-35+115\right)=57\cdot80=4560\)

\(35.\left(115-57\right)-115.\left(35-57\right)\\ =35.115-35.57-115.35+115.57\\ =\left(35.115-115.35\right)+\left(-35.57+115.57\right)\\ =0+57.\left(-35+115\right)\\ =57.80=4560\)

\(\text{35 ⋅ ( 115 − 57 ) − 115 ⋅ ( 35 − 57 )}\)

\(\text{= 35 ⋅ 115 − 35 ⋅ 57 − 115 ⋅ 35 + 115 ⋅ 57}\)

\(\text{= − 35 ⋅ 57 + 115 ⋅ 57}\)

\(\text{= 57 ⋅ 80 }\)

\(\text{= 4560}\)

1: =20*(-4)+24(-30)

=-80-720=-800

2: =-13*57+13*32+57*13-57*45

=13*32-57*45=-2149

3: =-12*8*125

=-12*1000=-12000

4: =(-134)(1-51+48)

=(-134)*(-2)=268

5: =(-24)(45-5)=40*(-24)=-960

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

2 . 53 . 27 + 6 . 9 . 87 - 3 . 18 . 40

= ( 2 . 27 ) . 53 + ( 6 . 9 ) . 87 - ( 3 . 18 ) . 40

= 54 . 53 + 54 . 87 - 54 . 40

= 54(53+87-40)

= 5400

12 . 25 + 29 . 25 + 59 . 25

= 25( 12 + 29 + 59 )

= 2500

43 . 37 + 93 . 43 + 57 . 61 + 69 . 57

= 43( 37 + 93 ) + 57(61 + 69 )

= 5590 + 7410

= 13000

12 . 53 + 53 . 172 - 53 

= 53( 12 + 172 ) - 53

= 9752 - 53

= 9699

35 . 54 + 35 . 58 + 65 . 75 + 65 . 45

= 35( 54 + 58 ) + 65( 75 + 45 )

= 3920 + 7800

= 11720

\(\left(19\frac{5}{8}:\frac{7}{12}-13\frac{1}{4}:\frac{7}{12}\right).\frac{4}{5}\)

\(=\left(\frac{157}{8}:\frac{7}{12}-\frac{53}{4}:\frac{7}{12}\right).\frac{4}{5}\)

\(=\left[\left(\frac{157}{8}-\frac{53}{4}\right):\frac{7}{12}\right].\frac{4}{5}\)

\(=\left[\frac{51}{8}:\frac{7}{12}\right].\frac{4}{5}\)

\(=\frac{153}{14}.\frac{4}{5}\)

\(=\frac{306}{35}\)

\(\left(\frac{-2}{5}+\frac{3}{7}\right)-\left(\frac{4}{9}+\frac{12}{20}-\frac{13}{35}\right)+\frac{7}{35}\)

\(=\frac{1}{35}-\frac{212}{315}+\frac{7}{35}\)

\(=\frac{1}{35}+\frac{-212}{315}+\frac{7}{35}\)

\(=\frac{9}{315}+\frac{-212}{315}+\frac{63}{315}\)

\(=\frac{-140}{315}=\frac{-4}{9}\)

\(\left(4\frac{5}{57}-3\frac{4}{51}+8\frac{13}{29}\right)-\left(3\frac{5}{57}-6\frac{16}{29}\right)\)

\(=\left(\frac{233}{57}-\frac{157}{51}+\frac{245}{29}\right)-\left(\frac{176}{57}-\frac{190}{29}\right)\)

\(=\frac{1941}{323}-\frac{-5726}{1653}\)

\(=\frac{14011}{1479}\)

\(\dfrac{3}{5}+\dfrac{2}{3}=\dfrac{9}{15}+\dfrac{10}{15}=\dfrac{19}{15}\\ \dfrac{5}{7}-\dfrac{1}{2}=\dfrac{10}{14}-\dfrac{7}{14}=\dfrac{3}{14}\\ \dfrac{5}{6}\times\dfrac{4}{5}=\dfrac{1}{3}\times\dfrac{2}{1}=\dfrac{2}{3}\\ \dfrac{7}{9}:\dfrac{4}{3}=\dfrac{7}{9}\times\dfrac{3}{4}=\dfrac{7}{12}\)

\(\dfrac{3}{5}+\dfrac{2}{3}=\dfrac{9}{15}+\dfrac{10}{15}=\dfrac{19}{15}\)

\(\dfrac{5}{7}-\dfrac{1}{2}=\dfrac{10}{14}-\dfrac{7}{14}=\dfrac{3}{14}\)

\(\dfrac{5}{6}\text{×}\dfrac{4}{5}=\dfrac{5\text{×}4}{6\text{×}5}=\dfrac{2}{3}\)

\(\dfrac{7}{9}:\dfrac{4}{3}=\dfrac{7}{9}\text{×}\dfrac{3}{4}=\dfrac{7\text{×}3}{9\text{×}4}=\dfrac{7\text{×}3}{3\text{×}3\text{×}4}=\dfrac{7}{12}\)

\(\dfrac{3}{5}+\dfrac{2}{3}=\dfrac{9}{15}+\dfrac{10}{15} = \dfrac{19}{15}\)

\(\dfrac{5}{7}-\dfrac{1}{2}=\dfrac{10}{14}-\dfrac{7}{14}=\dfrac{3}{14}\)

\(\dfrac{5}{6} \times \dfrac{4}{5} = \dfrac{4}{6}= \dfrac{2}{3}\)

\( \dfrac{7}{9} : \dfrac{4}{3} = \dfrac{7}{9} \times \dfrac{3}{4} = \dfrac{7}{12}\)

A = 1 3 − 1 3 + 3 5 − 3 5 + 5 7 − 5 7 + 7 9 − 7 9 + 9 11 − 9 11 + 11 13 − 11 13 + 13 15 = > A = 13 15 .

a) (-30) + 17 + (-70) + 33

=[-30+(-70)]+(17+33)

=-100+50

=-50

b) 56 - 15 - 6 + (-75)

=(56-6)-[15+(-75)]

=50-(-60)

=110

c) (157 - 56) - (44 + 57)

=157-56-44+57

=(-157-57)-(56+44)

=-100-100

=-200

d) (-24 + 174) - (174 - 24)

=-24+174-174+24

=(-24+24)+(174-174)

=0+0

=0

e) (35 - 47) - (-123 + 35) + [20 - (123 - 57)]

=35-47+123-35+[20-123+57]

=35-47+123-35+20-123+57

=(35-35)+(123-123)+(-47+57)

=0+0+(-10)

=-10

Bn sai ở câu e dòng 4

Còn câu f thì sao?

TK

a) (35 - 15).(-4) + 24.(-13 - 17)

= 20.(-4) + 24.(-30)

= (-80) + (-720)

b) (-13).(57 - 34) +57. (13 - 45)

= (-13).23 + 57.(-32)

= (-299) + (-1824) 

= -2123