Sửa đề: 100-98+96-94+...+52-50

=2+2+...+2

=2*13=26

100-98+96-94+92-90+...+52-50

=2+98-98+2+94-94+2+90-90+....+2+50-50

=2+2+2+...+2(có 13 số 2)

=2x13

=26

789. 2- 56+ (-95)+111+261+498-215+49+1236-4591-56+4189+48+52-1000-500+230+32500-5600+2641+853+195-564+235+4187+9023177-5000000+562+159-90+459-420+562+235+489+71+12

= 1578- 56+ (-95)+111+261+498-215+49+1236-4591-56+4189+48+52-1000-500+230+32500-5600+2641+853+195-564+235+4187+9023177-5000000+562+159-90+459-420+562+235+489+71+12

=1522+ (-95)+111+261+498-215+49+1236-4591-56+4189+48+52-1000-500+230+32500-5600+2641+853+195-564+235+4187+9023177-5000000+562+159-90+459-420+562+235+489+71+12

=1427+111+261+498-215+49+1236-4591-56+4189+48+52-1000-500+230+32500-5600+2641+853+195-564+235+4187+9023177-5000000+562+159-90+459-420+562+235+489+71+12

=1538+261+498-215+49+1236-4591-56+4189+48+52-1000-500+230+32500-5600+2641+853+195-564+235+4187+9023177-5000000+562+159-90+459-420+562+235+489+71+12

=1799+498-215+49+1236-4591-56+4189+48+52-1000-500+230+32500-5600+2641+853+195-564+235+4187+9023177-5000000+562+159-90+459-420+562+235+489+71+12

=2297-215+49+1236-4591-56+4189+48+52-1000-500+230+32500-5600+2641+853+195-564+235+4187+9023177-5000000+562+159-90+459-420+562+235+489+71+12

=2082+49+1236-4591-56+4189+48+52-1000-500+230+32500-5600+2641+853+195-564+235+4187+9023177-5000000+562+159-90+459-420+562+235+489+71+12

=2131+1236-4591-56+4189+48+52-1000-500+230+32500-5600+2641+853+195-564+235+4187+9023177-5000000+562+159-90+459-420+562+235+489+71+12

=3367-4591-56+4189+48+52-1000-500+230+32500-5600+2641+853+195-564+235+4187+9023177-5000000+562+159-90+459-420+562+235+489+71+12

=-1224-56+4189+48+52-1000-500+230+32500-5600+2641+853+195-564+235+4187+9023177-5000000+562+159-90+459-420+562+235+489+71+12

=-1280+4189+48+52-1000-500+230+32500-5600+2641+853+195-564+235+4187+9023177-5000000+562+159-90+459-420+562+235+489+71+12

=2909+48+52-1000-500+230+32500-5600+2641+853+195-564+235+4187+9023177-5000000+562+159-90+459-420+562+235+489+71+12

=2957+52-1000-500+230+32500-5600+2641+853+195-564+235+4187+9023177-5000000+562+159-90+459-420+562+235+489+71+12

=3009-1000-500+230+32500-5600+2641+853+195-564+235+4187+9023177-5000000+562+159-90+459-420+562+235+489+71+12

=2009-500+230+32500-5600+2641+853+195-564+235+4187+9023177-5000000+562+159-90+459-420+562+235+489+71+12

=1509+230+32500-5600+2641+853+195-564+235+4187+9023177-5000000+562+159-90+459-420+562+235+489+71+12

=1739+32500-5600+2641+853+195-564+235+4187+9023177-5000000+562+159-90+459-420+562+235+489+71+12

=34239-5600+2641+853+195-564+235+4187+9023177-5000000+562+159-90+459-420+562+235+489+71+12

=28639+2641+853+195-564+235+4187+9023177-5000000+562+159-90+459-420+562+235+489+71+12

=31280+853+195-564+235+4187+9023177-5000000+562+159-90+459-420+562+235+489+71+12

=32133+195-564+235+4187+9023177-5000000+562+159-90+459-420+562+235+489+71+12

=32328-564+235+4187+9023177-5000000+562+159-90+459-420+562+235+489+71+12

=31764+235+4187+9023177-5000000+562+159-90+459-420+562+235+489+71+12

=31999+4187+9023177-5000000+562+159-90+459-420+562+235+489+71+12

=36186+9023177-5000000+562+159-90+459-420+562+235+489+71+12

=9059363-5000000+562+159-90+459-420+562+235+489+71+12

=4059363+562+159-90+459-420+562+235+489+71+12

=4059925+159-90+459-420+562+235+489+71+12

=4060084-90+459-420+562+235+489+71+12

=4059994+459-420+562+235+489+71+12 

=4060453-420+562+235+489+71+12 

=4060033+562+235+489+71+12 

=4060595+235+489+71+12

=4060830+489+71+12

=4061319+71+12=4061402

ủa:q. rảnh v:))

a) \(-70+70\)

\(=-\left(70-70\right)\)

\(=-0\)

\(=0\)

c) \(\left(-11\right)+\left(-22\right)+\left(-33\right)\)

\(=-11-22-33\)

\(=-\left(11+22\right)-33\)

\(=-33-33\)

\(=-\left(33+33\right)\)

\(=-66\)

d) \(-840+560+\left(-160\right)\)

\(=-840+560-160\)

\(=-\left(840-560\right)-160\)

\(=-280-160\)

\(=-\left(280+160\right)\)

\(=-440\)

\(-99+98+\left(-97\right)+96+\left(-95\right)+94+\left(-93\right)+92+\left(-91\right)+90\)

\(=-99+98-97+96-95+94-93+92-91+90\)

\(=-\left(99-98\right)-\left(97-96\right)-\left(95-94\right)-\left(93-92\right)-\left(91-90\right)\)

\(=-1-1-1-1-1\)

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

\(=-2-1-1-1\)

\(=-\left(2+1\right)-1-1\)

\(=-3-1-1\)

\(=-\left(3+1\right)-1\)

​\(=-4-1\)​

\(=-\left(4+1\right)\)

\(=-5\)

1000+98+96+...+2 - (97+95+93+91+....+1)

=2450 - 2401

=49

Lời giải chi tiết:

\(100-99+98-97+96-95+94-93+92-91+90\)

\(=\left(100-99\right)+\left(98-97\right)+\left(96-95\right)+\left(94-93\right)+\left(92-91\right)+90\)

\(=1+1+1+1+1+90\)

\(=95\)

Cảm ơn Bạn nha!

thấy (100-99)+(98-97)+(96-95)+(94-93)+(92-91)+90

=1+1+1+1+1+90

=95

100 - 99 + 98 - 97 + 96 - 95 + 94 - 93 + 92 - 91 + 90 = 95