a: \(\dfrac{8}{18}+\dfrac{5}{3}=\dfrac{4}{9}+\dfrac{5}{3}=\dfrac{4}{9}+\dfrac{15}{9}=\dfrac{4+15}{9}=\dfrac{19}{9}\)

b: \(\dfrac{8}{24}+\dfrac{4}{48}=\dfrac{1}{3}+\dfrac{1}{12}=\dfrac{4}{12}+\dfrac{1}{12}=\dfrac{4+1}{12}=\dfrac{5}{12}\)

c: \(\dfrac{20}{15}-\dfrac{4}{45}=\dfrac{4}{3}-\dfrac{4}{45}=\dfrac{60}{45}-\dfrac{4}{45}=\dfrac{60-4}{45}=\dfrac{56}{45}\)

d: \(\dfrac{40}{32}-\dfrac{1}{2}=\dfrac{5}{4}-\dfrac{1}{2}=\dfrac{5-2}{4}=\dfrac{3}{4}\)

45-58+(-45)+(+58)-3=45-58-45+58-3=(45-45)+(58-58)-3=-3

(-57)-(-12)+3-(-57)=-57+12+3+57=(-57+57)+12+3=15

-(-24)-(-30)+(-24)-30+8=24+30-24-30+8=(24-24)+(30-30)+8=8

-(-12)+(+19)-(+12)+8-19=12+19-12+8-19=(12-12)+(19-19)+8=8

47-(-53)+(-47)-(+53)=47+53-47-53=(47-47)+(53-53)=0

-(+28)+32-(-28)+(-34)=-28+32+28-34=(-28+28)-(34-32)=-2

15-(+72)+(-15)+(+72)=15-72-15+72=(15-15)+(72-72)=0

20-(+46)+(-25)-(-46)=20-46-25+46=(20-25)+(46-46)=-5

28-(-32)+(-28)-32+5=28+32-28-32+5=(28-28)+(32-32)+5=5

-75+(-49)+(+75)+49-12=-75-49+75+49-12=(-75+75)+(49-49)-12=-12

\(...=45-58-45+58-3=-3\)

\(...=-57+12+3+57=15\)

\(...=24+30-24-30+8=8\)

\(...=12+19-12+8-19=8\)

\(...=47+53-47-53=0\)

\(...=-28+32+28-34=-2\)

\(...=15-72-15+72=0\)

\(...=20-46-25+46=-5\)

\(=...28+32-28-32+5=5\)

\(...=-75-49+75+49-12=-12\)

Bài 1 :

a) 37581 - 9999 = 37581 - 10000 - 1 = 27581 - 1 = 27580

k cho mình nha bạn ! 

a)37581-9999=37581-(9999+1-1)=37581-(10000+1)=37581-10000-1=27581+1=27582

1. -28 + 32

2. 50 + 21

3. (-45) + (-30)

4. x + (-80)

5. 7 + (-a)

6. -25 + a

\(\frac{48x700-24x45x20}{45-40+35-30+25-20+15-10}\)

\(=\frac{24x2x700-24x45x20}{5+5+5+5}\)

\(=\frac{24x1400-24x900}{20}\)

\(=\frac{24x\left(1400-900\right)}{20}\)

\(=\frac{24x500}{20}\)

\(=\frac{12000}{20}\)

\(=600\)

k nha

 

\(\frac{27x45+27x55}{2+4+6+...+16+18}\)

\(=\frac{27x\left(45+55\right)}{2+4+6+...+16+18}\)

\(=\frac{27x100}{2+4+6+...+16+18}\)

\(=\frac{2700}{\left(2+18\right)x9:2}\)

\(=\frac{2700}{90}\)

\(=30\)

k nha

 

\(\frac{26x108-26x12}{32-28+24-20+16-12+8-4}\)

\(=\frac{26x\left(108-12\right)}{4+4+4+4}\)

\(=\frac{26x96}{16}\)

\(=\frac{2496}{16}\)

\(=156\)

k nha

a) x = 74    

b) x = 5 

c) x = 3      

d) x = 14

a) 135 . (-27) + 27 . 235

= 27 . (235 - 135)

= 27 . 100

= 2700

b) 36 . (-125) - 125 . (-46)

= 125 . (-36 + 46)

= 125 . 10

= 1250

c) 32 . (-64) - 64 . 68

= 64.(-32 - 68)

= 64.(-100)

= -6400

d) (145 - 45) . (-31) + 31 . (-100)

= 100 . (-31) + 31.(-100)

= 100.(-31 - 31)

= 100.(-62)

= -6200

a)

=(-135)x27+27x235

=27x[+(235+135)]

=27x31725

=856575

b)

=(-36)x125-125x(-46)

=125x[-(36+46)]

=125x(-1656)

=-207000

c)

=(-32)x64-64x68

=64x[-(68-32)]

=64x(-36)

=-(64x36)

=-2304

d)

=100x(-31)+31x(-100)

=(-100)x31+31x(-100)

=31x[-(100+100)]

=31x(-200)

=-(31x200)

=-6200

chúc học tốt nhớ tích cho tui nha

nếu tui đúng chứ tui cũng hông có chắc nữa

Bài 3:

a: Ta có: \(23\left(42-x\right)=23\)

\(\Leftrightarrow42-x=1\)

hay x=41

b: Ta có: 15(x-3)=30

nên x-3=2

hay x=5

Bài 1: 

a: 32+89+68=100+89=189

b: 64+112+236=300+112=412

c: \(1350+360+650+40=2000+400=2400\)