Ta có:

\(\left(16\times6+16\times3+16\right)-12\times65-12\times3-2\times12\)

\(=16\times\left(6+3+1\right)-\left(12\times65+12\times3+2\times12\right)\)

\(=16\times10-12\left(65+3+2\right)\)

\(=160-12\times80\)

\(=160-960\)

\(=-800\)

theo mình nhớ thì toán lớp 3 ko có số âm nên bạn coi thử đề có sai ko ???

sai đề không em ơi, kết quả ra số âm, mà số âm ko học ở lớp 3

sai đề vì lớp 3 đâu có hok số âm đâu

Bài 1 bạn tự là nhé dễ lắm :))

Bài 2 :

Ta có :

\(4x-15=-75-x\)
\(\Leftrightarrow\)\(4x+x=-75+15\)

\(\Leftrightarrow\)\(5x=-60\)

\(\Leftrightarrow\)\(x=\frac{-60}{5}\)

\(\Leftrightarrow\)\(x=-12\)

Bài 3 :

Ta có :

\(12⋮\left(x-3\right)\)\(\Rightarrow\)\(\left(x-3\right)\inƯ\left(12\right)\)

Mà \(Ư\left(12\right)=\left\{1;-1;2;-2;3;-3;4;-4;6;-6;12;-12\right\}\)

Suy ra : ( lập bảng )

Vậy \(x\in\left\{4;2;5;1;6;0;7;-1;9;-3;15;-9\right\}\)

Chúc bạn học tốt 

a) \(\dfrac{25}{37}\times\dfrac{18}{29}+\dfrac{18}{29}\times\dfrac{12}{37}\)

\(=\dfrac{18}{29}\times\left(\dfrac{25}{37}+\dfrac{12}{37}\right)\)

\(=\dfrac{18}{29}\times\dfrac{37}{37}\)

\(=\dfrac{18}{29}\times1\)

\(=\dfrac{18}{29}\)

b) \(\dfrac{31}{85}\times\dfrac{11}{19}+\dfrac{31}{85}\times\dfrac{12}{19}-\dfrac{42}{19}\times\dfrac{31}{85}\)

\(=\dfrac{31}{85}\times\left(\dfrac{11}{19}+\dfrac{12}{19}-\dfrac{42}{19}\right)\)

\(=\dfrac{31}{85}\times\dfrac{-19}{19}\)

\(=\dfrac{31}{85}\times-1\)

\(=-\dfrac{31}{85}\)

c) \(\dfrac{16}{53}:\dfrac{17}{9}-\dfrac{16}{53}:\dfrac{17}{8}\)

\(=\dfrac{16}{53}:\left(\dfrac{9}{17}-\dfrac{8}{17}\right)\)

\(=\dfrac{16}{53}:\dfrac{1}{17}\)

\(=\dfrac{16}{901}\)

c) \(\dfrac{1}{5}\times\dfrac{12}{31}\times\dfrac{4}{3}+\dfrac{19}{31}\times\dfrac{4}{15}\)

\(=\dfrac{4}{15}\times\dfrac{12}{31}+\dfrac{19}{31}\times\dfrac{4}{15}\)

\(=\dfrac{4}{15}\times\left(\dfrac{12}{31}+\dfrac{19}{31}\right)\)

\(=\dfrac{4}{15}\times\dfrac{31}{31}\)

\(=\dfrac{4}{15}\times1\)

\(=\dfrac{4}{15}\)

a: =18/29*(25/37+12/37)

=18/29

b: =31/85(11/19+12/19-42/19)

=-31/85

c; =16/53(9/17+8/17)=16/53

d: =4/15(12/31+19/31)=4/15

a) 1 + 1/4 + 1/8 + 1/16

= 16/16 + 4/16 + 2/16 + 1/16

= 23/16

b) 2 - 1/8 - 1/12 - 1/16

= 96/48 - 6/46 - 4/48 - 3/48

= 83/48

c) 4/99 × 18/5 : 12/11 + 3/5

= 8/55 : 12/11 + 3/5

= 2/15 + 3/5

= 2/15 + 9/15

= 11/15

d) (1 - 3/4) × (1 + 1/3) : (1 - 1/3)

= 1/4 × 4/3 : 2/3

= 1/3 : 2/3

= 2

1 + 1/4 + 1/8 + 1/16

= 16 + 4 + 2 + 1 / 16

=23/16

2-1/8-1/12-1/16

= 96 - 6 - 4 - 3 / 48

= 83 / 48

4/99 x 18/5 : 12 /11 + 3/5

= 4/99 x 18/5 x 11/12 + 3/5

= 2/15 + 3/5

= 11/15

(1 - 3/4) x (1+1/3) : (1-1/3) 

= 1/4 x 4/3 : 2/3

= 1/4 x 4/3 x 3/2

= 1/2

a)

− 12 . x = − 15 . − 4 − 12 − 12 . x = 60 − 12 − 12 . x = 48                x = 48 : − 12                x = − 4

b) 

− 9 . x + 3 = − 2 . − 7 + 16 − 9 . x + 3 = 14 + 16 − 9 . x + 3 = 30 − 9 . x           = 30 − 3 − 9 . x           = 27              x           = 27 : − 9              x           = − 3

c)

− 12 . x − 34 = 2 − 12 . x               = 2 + 34 − 12 . x               = 36                x                = 36 : − 12                x                = − 3

a)

− 12 . x = − 15 . − 4 − 12 − 12 . x = 60 − 12 − 12 . x = 48                x = 48 : − 12                x = − 4

b)

− 9 . x + 3 = − 2 . − 7 + 16 − 9 . x + 3 = 14 + 16 − 9 . x + 3 = 30 − 9 . x           = 30 − 3 − 9 . x           = 27              x           = 27 : − 9              x           = − 3

c) 

− 12 . x − 34 = 2 − 12 . x               = 2 + 34 − 12 . x               = 36                x                = 36 : − 12                x                = − 3

a) \(\left(12-12\dfrac{1}{3}\right):x+\dfrac{1}{6}=-\dfrac{2}{3}\)

\(-\dfrac{1}{3}x=-\dfrac{2}{3}-\dfrac{1}{6}\)

\(-\dfrac{1}{3}x=-\dfrac{5}{6}\)

\(x=-\dfrac{5}{6}:\left(-\dfrac{1}{3}\right)\)

\(x=\dfrac{5}{2}\)

b) \(\dfrac{4}{x}=\dfrac{x}{16}\)

\(x^2=4.16\)

\(x^2=64\)

\(\Rightarrow x=8;x=-8\)

`a)=>(12-37/3):x+1/6=-2/3`

`=>(12-37/3):x=-5/6`

`=>(-1/3):x=-5/6`

`=>x=(-1/3):(-5/6)`

`=>x=6/15=2/5`

`b)4/x=x/16`

`=>x^2=4*16`

`=>x^2=64`

`=>x^2=(+-8)^2`