1+2-3-4+5+6-7-8+9+9+10-11-12+12+...229-300+301+302
=(302+1)-(301+2)-(300+3)+(299+4)-...
=303-303-303-303-....
=0-0-0-0-0-....
=0
1+2-3-4+5+6-7-8+9+10-11-12+...-229-300+301+302
= (1+2-3)+(4+5+6-7)+...+(228-229-300+301)+302
= 0 + 0 +...+ 0 + 302
= 302
1+2-3-4+5+6-7-8+9+9+10-11-12+12+...229-300+301+302
=(302+1)-(301+2)-(300+3)+(299+4)-...
=303-303-303-303-....
=0-0-0-0-0-....
=0
1+2-3-4+5+6-7-8+9+10-11-12+...-229-300+301+302
= (1+2-3)+(4+5+6-7)+...+(228-229-300+301)+302
= 0 + 0 +...+ 0 + 302
= 302
1+2-3-4+5+6-7-8+9+10-11-12+...-299-300+301+302 = ?
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+14-...-299-300+301+302 =?
Ti'nh Tong
D = 1 +2 - 3 -4 + 5 + 6 - 7- 8 + 9 +10 - 11 -12 + ....... - 299 - 300 +301 +302
Tinh nhanh
A = 1 + 2 - 3 - 4 + 5 + 6 - 7 - 8 + 9 + 10 - 11 - 12 + ......... + 299 - 300 + 301 + 302
Tính nhanh :
1+2-3-4+5+6-7-8+9+10-11-12+13+14-...-299-300+301+302
b=1=2-3-4+5+6-7-8+9+10-11-12+......+301+302
1+2-3-4+5+6-7-8+9+10-11-12+13+....+298-299-300+301+302
Tính giá trị biểu thức sau một cách hợp lí
1+2-3-4+5+6-7-8+9+10-11-12+13+14-15-16+...+301+302