1+2-3-4+5+6-7-8+9+10-11-12+....-299-300+301-302
1+2-3-4+5+6-7-8+9+10-11-12+...-299-300+301+302 = ?
Ta chia thành: 1 + (2-3-4+5) + (6-7-8+9)+....+(298-299-300+301) + 302 = 1 + 0 + 0 + 0 + .....+ 0 + 302 = 1+302 = 303
1 + 2 - 3 - 4 + 5 + 6 - 7 - 8 + 9 + 10 - 11 - 12 +........- 299 -300 + 301 +302
1 + 2 - 3 - 4 + 5 + 6 - 7 - 8 + 9 + 10 - 11 - 12 +........- 299 -300 + 301 +302
Theo đề ta có:
Cho A= 1 + 2 - 3 - 4 + 5 + 6 - 7 - 8 + 9 + 10 - 11 - 12 +........- 299 -300 + 301 +302
=> 1 + (2 - 3 - 4 + 5 )+ (6 - 7 - 8 + 9) + (10 - 11 - 12 +13)........(289- 299 -300 + 301) +302
=> 1+ 0+ 0+.....+ 0+ 302
=> 1+302
=> 303
1+2-3-4+5+6-7-8+9+10-11-12+...-299-300+301+302
Ta chia thành: 1 + (2-3-4+5) + (6-7-8+9)+....+(298-299-300+301) + 302 = 1 + 0 + 0 + 0 + .....+ 0 + 302 = 1+302 = 303
**** cho mk nha bạn !!!
1+2-3-4+5+6-7-8+9+10-11-12+...-299-300+301+302
1+2-3-4+5+6-7-8+9+10-11-12+.....-299-300+301+302
=1+(2-3)+(-4+5)+(6-7)+(-8+9)+(10-11)+... +(-300+301)+302
= 1-1+1-1+1-1+...-1+302
= 302
Học tốt
@Trung
302 nha bạn hok tốt
1+2-3-4+5+6-7-8+9+10-11-12+...-299-300+301+302
1+2-3-4+5+6-7-8+9+10-11-12+...+299-300+301+302
=1+(2-3-4+5)+(6-7-8+9)+(10-11-12+13)+...+(298-299-300+301)+302
=1+0+0+0+...+0+302
=1+302
=303
1+2-3-4+5+6-7-8+9+10-11-12+...-299-300+301+302
=(1+2-3)+(4+5+6-7)+...+(298-299-300+301)+302
= 0 + 0 +...+ 0 + 302
=302
1+2-3-4+5+6-7-8+9+10-11-12+..........-299-300+301+302
1+2-3-4+5+6-7-8+9+10-11-12+13...............-299-300+301+302
= 1 + (2-3-4+5)+(6-7-8+9) + (10-11-12+13)+.......................+(298-299-300+301)+302
= 1 + 0 + 0 + 0 + .......................+ 0 + 302
= 303
1+2-3-4+5+6-7-8+9+10-11-12+..........-299-300+301+302
= ( 1 + 2 - 3 ) - ( 4 + 4 + 6 - 7 ) + ............ - ( 299 - 300 + 301 ) + 302
= 0 - 0 + ............. - 0 + 302
= 302
nhớ ủng hộ mik nha mn
B=1+2-3-4+5+6-7-8+9+10-11-12+.........-299-300+301+302 = ?
1+2‐3‐4+5+6‐7‐8+9+10‐11‐12+...‐229‐300+301+302
= (1+2‐3)+(4+5+6‐70)+...+(228‐229‐300+301)+302
= 0 + 0 +...+ 0 + 302 = 302
B = 1+2-3-4+5+6-7-8+9+10-11-12+..........-299-300+301+302
B = 1+(2-3-4+5)+(6-7-8+9)+.......+(298-299-300+301)+302
B = 1+0+0+....+0+302
B = 1+302
B = 303
B= 1+2-3-4+5+6-7-8+9+10-11-12+...-299-300+301+302
B = 1+2-3-4+5+6-7-8+9+10-11-12+...-299-300+301+302( có 302 số, 302 chia 4 dư 2)
B = 1+(2-3-4+5)+(6-7-8+9)+(10-11-12+13)+...+(298-299-300+301)+302
B = 1 + 0 + 0 + 0 + ... + 0 + 302
B = 303 + 0
B = 303
1+2-3+5+6-7-8+...-399-400
Ta có
(1+2-3)+(-4+5+6-7)+(-8+9+10-11)+...
+(-396+396+398-399)-400
=0+0+0+...+0-400
=-400
, B = 1+2-3-4+5+6-7-8+9+10-11-12+...-229-330+301+302
B = ( 228 - 226 + 227 - 225 + ... - 6 - 4 + 5 - 3 ) +2 + 1 +301+302 -229-330
( Từ 228 đến 2 có số cặp hiệu là : ( 228 - 3 + 1 ) : 2 = 113, mà mỗi cập hiệu có kq là 2 )
B = 113 x 2 +2 + 1 +301+302 -229-330
B = 229 - 229 + 603 - 330
B = 273
Vậy B = 273
1+2-3-4+5+6-7-8+9+10-11-12+........+298-299-300+301+302 = ?
1+2-3-4+5+6-7-8+9+10-11-12+........+298-299-300+301+302 =
1+2+(5-3)+(6-4)+(9-7)+(10-8)+…….+(301-299)+(302-300)=
Từ 302 đến 3 có số cặp là [(302-3):1+1]:2=150 cặp. Mà mỗi cặp có giá trị là 2
Vậy 1+2-3-4+5+6-7-8+9+10-11-12+........+298-299-300+301+302 =
1+2+2×150=3+300=303