a) 234-117+(-100)+(-234)

=234+(-234)-117+(-100)

=0-117-100

=(-117)-100

=-217

b) -927+1421+930+(-1421)

=[-927+930]+[1421-1421)]

=3+0

=3

Câu 2: a) 234-117+(-100)+(-234)=[234+(-234)]-117-100=0-117-100=-217

b) -927+1421+930+(-1421)=-927+930+[1421+(-1421)]=-927+930+0=3

Bài 1:

s1=1+(-3)+5+(-7)+............+17

s2=-2+4+(-6)+8+...........+(-18)
\(\Rightarrow\) s1 + s2 = (1-2-3+4)+(5-6-7+8)+...+(13-14-15+16)+17-18

= 0 + 0 + ...+ 0 + (-1)

= -1

Bài 2.

a) 234-117+(-100)+(-234)

= (-234 + 234 ) + [- 117 + (-100)]

= 0 + (-217)

= -217

b) -927+1421+930+(-1421)

= ( -1421 + 1421 ) + ( -927 + 930 )

= 0 + 3

= 3

(187-23)-(20-180)                                      (187-23)-(20-180)

(187-180)-(23-20)                                       164-(-160)

7-3                                                               4

4

làm theo cách nào thì làm nhó

a) 234 - 117 + (-100) + (-234) = [234 + (-234)] - [117 + (-100)] = 0 + 17 = 17.

b) (-927) + 1421 + 930 + (-1421) = [(-927) + 927)] + (1421 + 930) = 0 + 2351 = 2351.

c) 11 - 12 + 13 - 14 + 15 - 16 + 17 -18 + 19 - 20 = (11 - 20) + (12 - 19) + (13 - 18) + (14 - 17) + (15 - 16)

= (-9) + (-7) + (-5) + (-3) + (-1) = -25.

d) 101 - 102 - (-103) - 104 - (-105) - 106 - (-107) - 108 - (-109) - 110

= (-101) + (-102) + 103 + (-104) + 105 + (-106) + 107 + (-108) + 109 + (-110)

=               (-203) +                      (-205) +           (-204) +           (-203) + (-110)

= -925.

e) (-125) + 100 + 80 + 125 + 20 = [(-125) + 125] + 100 + (80 + 20) = 0 + 100 + 100 = 200.

23-(-27)+(-50) = 0

234+(-117)-100+(-234) = -217

-927-(-1421)-(930)+(-1421) = -1020

2021-[-2022-(-2021)] = 2021

1-2+3-4+...+2021-2022= 

A=1-2+3-4+...+2021-2022

=(1-2)+(3-4)+...+(2021-2022)  (có tất cả 1011 cặp)

=(-1).(-1)...(-1)

=(-1).1011=-1011

HOk tốt!!!!!!!!!!!!!

23 - ( - 27 ) + ( - 50 ) = 0

234 + ( - 117 ) - 100 + ( - 234 ) = - 217

- 927 - ( - 1421 ) - ( 930 ) + ( - 1421 ) = 985

2021 - [ - 2022 - ( - 2021 )] = 2022

1 - 2 + 3 - 4 + ...+ 2021 - 2022 

=(1-2)+(3-4)+...+(2021-2022)

=(-1)+(-1)+...

=(-1)x(2022:2)

= -1011

\(a)23-\left(-27\right)+\left(-50\right).\)

\(=23+27-50\)

\(=50-50=0\)

\(b)234+\left(-117\right)-100+\left(-234\right)\)

\(=\left[234+\left(-234\right)\right]+\left[\left(-117\right)-100\right]\)

\(=0+\left(-217\right)\)

\(=-217\)

\(c)-927-\left(-1421\right)-\left(-930\right)+\left(-1421\right)\)

\(=-927+1421+930-1421\)

\(=\left(-927+930\right)+\left(1421-1421\right)\)

\(=3+0=3\)

\(d)2021-\left[-2022-\left(-2021\right)\right]\)

\(=2021-\left(-2022+2021\right)\)

\(=2022\)

\(e)1-2+3-4+...+2021-2022\)

\(=\left(1-2\right)+\left(3-4\right)+...+\left(2021-2022\right)\)

\(=-1+\left(-1\right)+...+\left(-1\right)\)

\(=-1\times1011\)

\(=-1011\)

\(#Wee\)

a,    243 -117 +(-100)+(-234)

= [243 +(-234)]  + [117 +(-100)]

=9+17

=26

b,    (-927)+1421+930+(-1421)

=[1421+ (-1421)] +[(-927)+930]

=0+3

=3

a, 243 - 117 + ( - 100 ) + ( - 234 )

= 126 + ( - 100 ) + ( - 234 )

= 26  + ( - 234 )

= - 208

a) 243 - 117 + (-100) + (-234)

= [234 - (-234)] + [(-100) + 117]

= 0                     + 17

= 17

b)(-927) + 1421 + 930 + (-1421)

= [1421 + (-1421) + [(-927) + 930]

= 0                        + -3

= -3

)hai số đối nhau có tổng bằng 0                       nhớ