-39

-12

tick nha

=(768-768)-39=0-39=-39

=(-1589)-(-157)-12=0-12=-12

a) ( 768 - 39 ) - 768

= 768 - 39 - 768

= ( 768 - 768 ) - 39

= 0 - 39

= -39

b) ( -1579 ) - ( 12 - 1579 )

= -1579 - 12 + 1579

= ( 1579 - 1579 ) - 12

= 0 - 12

= -12

a) ( 768 - 39 ) - 768

= 768 - 39 - 768

= ( 768 - 768 ) - 39

= 0 - 39

= -39

b) ( -1579 ) - ( 12 - 1579 )

= ( -1579 ) - 12 + 1579

= ( -1579 + 1579 ) - 12

= 0 + -12

= -12

a) \(\left(768-39\right)-768=768-39-768=768-768-39=0-39=-39\)

b)\(\left(-1579\right)-\left(12-1579\right)=\left(-1579\right)-12+1579=\left[\left(-1579\right)+1579\right]-12=0-12=-12\)

a. (768 - 39) - 768

= 768 - 39 - 768

= 768 - 768 - 39

= 0 - 39

= -39

b. (-1579) - (12 - 1579)

= (-1579) - 12 + 1579

= [(-1579) + 1579] - 12

= 0 - 12

= -12

chờ mình xíu

1a,=-2*3=-6                      b,=2*3=6

2a,=-39         b,=-12

B1 :

a, = -2-2-2= -6

b, = -2-2-2 = -6

B2:a, = 768-39-768 = (768-768)-39=0-39=-39

b, = -1579-12+1579 = (-1579+1579)-12 = 0-12=-12

k mk nha

Bài 1 : Tính : 

a, 1+(-3)+5+(-7)+9+(-11)

= ( -2 ) + 5 + ( -7 ) + 9 + ( -11 )

= 3 + ( -7 ) + 9 + ( -11 )

= ( -4 ) + 9 + ( -11 )

= 5 + ( -11 )

= ( -6 )

b, (-2)+4+(-6)+8+(-10)+12.

= 2 + ( -6 ) + 8 + ( -10 ) + 12

= ( -4 ) + 8 + ( -10 ) + 12

= 4 + ( -10 ) + 12

= 6 + 12

= 18

Bài 2 : Tính nhanh :

a, (768-39)-768

= 768 - 39 - 768

= ( 768 - 768 ) - 39

= 0 - 39

= ( -39 ) 

b, (-1579)-(12-1579).

= ( -1579 ) - 12 + 1579

= [ ( -1579 ) + 1579 ) ] - 12

=  0 - 12

= ( -12 )

a. (768-39)-768

= 768-39-768

= (768-768)-39

= 0-39=-39

b. (-579)-(12-1579)

= -579-12+1579

= (1579-579)-12

= 1000-12=988.

a) -39

b) 988

tick nha

( -1579 ) – ( 12 – 1579 )

= -1579 + 1579 – 12

= 0 – 12

= - 12

\(3)1579-(53+1579)-(53) \)

\(=1579-53-1579+53\)

\(=(1579-1579)-(-53+53)\)

\(=0-0\)

\(=0\)

\(4)2001-15+54-2001-54\)

\(=(2001-2001)+(54-54)-15\)

\(=0+0-15\)

\(=0-15\)

\(=-15\)

Bài 1. Bỏ ngoặc rồi tính

a) 1579 - ( 53 + 1579 ) - (-53)

=1579 - 53 - 1579 + 53 

= 0 

b) 15766 - ( 14 - 53 ) + ( - 15566)

=15766 - 14 + 53 -15566

= 200 + 39 

= 239

c) 2486 + ( -486) - ( - 697) - ( + 97) + 58

= 2486 - 486 +697 -97 +58

= 2000 + 658

=2658

Bài 1. Bỏ ngoặc rồi tính

a) 1579 - ( 53 + 1579 ) - (-53)

= 1579 - 53 - 1579 + 53

= 0 

b) 15766 - ( 14 - 53 ) + ( - 15566)

= 15766 - 14 + 53 - 15566

= 239

c) 2486 + ( -486) - ( - 697) - ( + 97) + 58

= 2486 - 486 + 697 - 97 + 58

= 2000 + 600 + 58

= 2658

Bài 2. Tìm x, biết

a) | x | = 2

\(\Leftrightarrow\orbr{\begin{cases}x=2\\x=-2\end{cases}}\)

b) | x + 7 | = 8

\(\Leftrightarrow\orbr{\begin{cases}x+7=8\\x+7=-8\end{cases}\Leftrightarrow\orbr{\begin{cases}x=1\\x=-15\end{cases}}}\)

c) | x - 6 | - 5 = ( -4) + 20

\(\Leftrightarrow\text{| x - 6 | = 21}\)

\(\Leftrightarrow\orbr{\begin{cases}x-6=21\\x-6=-21\end{cases}\Leftrightarrow\orbr{\begin{cases}x=27\\x=-15\end{cases}}}\)

2001- ( 53 + 1579 ) - ( -53)= 2001 - 1632 - ( -53)

                                      = 368 - ( -53)

                                      = 422

\(2001-\left(53+1579\right)-\left(-53\right)\)

\(=2001-53-1579+53\)

\(=2000+1-1500-79\)

\(=500-79+1\)

\(=421+1\)

\(=422\)

422 nha bạn