5+6+7+8+9+10+11+........................................................................................................................+100+101
-3-4+5+6-7-8+9+10+11+....+99-100+101+102-103
Giúp mình vs ạ
1×2×3×4×5×6×7×8×9×10×11×12×13...×100×101×102=?
bài làm
x+1+2+3+....+100 = 250000
x = 250000 - 5050
x = 2244950
hacker 2k6
1 + 2 + 3 - 4 - 5 - 6 + 7 + 8 + 9 - 10 - 11 - 12 + ... + 97 + 98 - 100 - 101 - 102
1 + 2 + 3 - 4 - 5 - 6 + 7 + 8 +9 - 10 - 11- 12 +..... + 97 + 98 + 99 - 100 - 101 - 102
1+2+3-4-5-6+7+8+9-10-11-12+.........+97+98+99-100-101-102
1+2+3-4-5-6+...+97+98+99-100-101-102
=(1+2+3-4-5-6)+...+(97+98+99-100-101-102) có 17 cặp số
=(-9)+(-9)....+(-9) 17 cặp số
=(-9).17=-153
1+2+3-4-5-6+7+8+9-10-11-12+...+97+98+99-100-101-102
1+2-3-4+5+6-7-8+9+10-11-12+13+98-99-100+101+102
ủa tính nhanh hay tính giá trị biểu thức hay tính thường dợ bên đó
1+2-3-4+5+6-7-8+9+10-11-12+13+98-99-100+101+102 = 103
1+2-3-4+5+6-7-8+9+10-11-12+13+98-99-100+101+102
= 1 + (2-3-4+5)+(6-7-8+9)+(10-11-12+13)+(98-99-100+101)+102
= 1 + 0 + 0 + 0 + 0 +102
= 103
D= 1+2+3-4-5-6+7+8+9-10-11-12+........+97+98+99-100-101-102
iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiilllllllllllllllllllllllllllljjjjhhhhhhhgfheeehgt
D = 1+2+3-4-5-6+7+8+9-10-11-12+........+97+98+99-100-101-102
D = (1+2+3-4-5-6) + (7+8+9-10-11-12) + ........... + (97+98+99-100-101-102)
D = (-9) + (-9) + .......... + (-9) có 17 số -6
D = -6.(-9)
D = 54
Tính tổng : a) S2 = 1 - 3 + 5 - 7 + 9 - 11 + ... + 2005 - 2007. b) S3 = 1 + 2 + 3 - 4 - 5 - 6 + 7 + 8 + 9 - 10 - 11 - 12 + ... + 97 + 98 + 99 - 100 - 101 - 102