a) 1968 x 15 + 1968 x 84 + 1968

= 1968 x 15 + 1968 x 84 + 1968 x 1

= 1968 x (15 + 84 + 1)

= 1968 x 100 = 196800

b) 6412 + 5378 + 3582 + 4628

= (6412 + 5378) + (3582 + 4628)

= 11790 + 8210

= 20000

c) 178 x 101 - 178

= 178 x 101 - 178 x 1

= 178 x (101 - 1)

= 178 x 100

= 17800

d) 153 x 8 + 153 + 153

= 153 x 8 + 153 x 1 + 153 x 1

= 153 x (8 + 1 + 1)

= 153 x 10

= 1530

Bài 1:

a. Ta có: $1953=3^2.7.31$

$777=3.7.37$

$\Rightarrow UCLN(1953, 777) = 3.7=21$

b. Đề khó hiểu quá. Bạn xem lại/

Bài 2: Thiếu dấu giữa các số. Bạn xem lại.

a, ( x - 10 ) x ( 2 - x ) = 0 

=>x - 10 =0  hoặc 2 - x =0

    x =0+10                 x  =2-0

vậyx=10        hoặc      x =2

c, 70 - 5 x ( 2 x + 6 ) = 64

5 x ( 2 x + 6 ) = 70-64

5 x ( 2 x + 6 ) = 6

 2 x + 6=6:5

 2 x + 6=1,2

2 x=1,2-6

2 x=-4,8

x=-4,8:2

x=-2,4

d, ( 61 + ( 53 - x ) ) x 17 = 178

 61 + ( 53 - x )=178:17

 61 + ( 53 - x )=178/17

53 - x =178/78-61

53 - x =-859/17

x=53-(-859/17)

x=1760/17

(x - 10) x (2-x) = 0

Trường hợp 1: x - 10 = 0

=> x = 10

Trường hợp 2: 2 - x = 0

=> x = 2

Vậy x = 10 hoặc x = 2

Tương tự          

a )531 + ( 218 - x ) = 735

218 - x = 735 - 531

218 - x = 204

x = 218 - 204

x = 14

a ) 541 + ( 218 - x ) = 735

218 - x = 735 - 541

218 - x = 194

x = 218 - 194

x = 24

d,\(\left(x-5\right)\cdot\left(x-7\right)=0\Rightarrow\orbr{\begin{cases}x-5=0\\x-7=0\end{cases}\Rightarrow}\orbr{\begin{cases}x=5\\x=7\end{cases}}\)

a, 56 x 12 + 24 x 36 + 24 x36 = 56 x 12 + 12 x 2 x 36 + 12 x 2 x 36

                                                   = 56 x 12 + 12 x 72 + 12 x 72

                                                   = 12 x ( 56 + 72 +  72 )

                                                   = 12 x 200

                                                     = 2400

b, 2005 x 178 - 77 x 2005 - 2005 = 2005 x ( 178 - 77 - 1 )

                                                          = 2005 x 100

                                                           = 200500

**** mình nha nguyễn thùy trang

Nhìn vào đề bài,ta làm tiếp:

=178x(96+3+2-1)

=178x100

=17800

k cho mik nha

178 x  96 + 3 x 178 + 178 x 2 - 178 

= 178 x ( 96 + 3 + 2 - 1 )

= 178 x (96 + 5  - 1 )

= 178 x ( 96 + 4 ) 

= 178 x 100 

= 17800

178 x 96 + 3 x 178 + 178 x 2 - 178 

= 178 x 96 + 178 x 3 + 178 x 2 - 178 x 1

= 178 x ( 96 + 3 + 2 - 1 )

= 178 x 100

= 17800

b,\(96-3\left(x+1\right)=42\Rightarrow96-42=3\left(x+1\right)\Rightarrow54=3\left(x+1\right)\Rightarrow x+1=54\div3=18\Rightarrow x=18-1=17\)
d,\(\left[178-\left(13x-8\right)\right]\cdot53=5724\Rightarrow178-\left(13x-8\right)=5724\div53=108\Rightarrow178-108=13x-8\Rightarrow13x-8=70\Rightarrow13x=70+8=78\Rightarrow x=78\div13=6\)

 = 178 - 2013 - ( -178 -2013 ) +2 

 = 178 -2013 +178 +2013 +2 

 = 2

Trả lời:

\(178-2013-\left[-178+\left(-2013\right)\right]+2\)

\(=178-2013+178+2013+2\)

\(=\left(178+178\right)+\left(2013-2013\right)+2\)

\(=356+0+2\)

\(=358\)

Hok tốt!

Vuong Dong Yet