1+(1+2)+(1+2+3)+...+(1+2+3+...+98)
_____________________________
1*98+2*97+3*96+....+98*1
1/1+2+1/2+3+1/3+4+...+1/98+99+1/99+100
Tính:
1/1+2 +1/1+2+3 +1/1+2+3+4 +...........+1/1+2+3+4+5+...+98+99+100
A = 1-2+3-4+5-6+.....+97-98+99-100+101
B = 1+2-3-4+5+6-7-8+......+98-99-100+101
(1+1/2)*(1+1/3)*..........................(1+1/98)*(1+1/99)
Tính tổng
a, 1 + 2 = 3 + 4 + ....... + 98 + 99
b, 1 + 3 + 5 + 7 + .......... + 97 +99
c, 2 + 4 + 6 + 8 +.........+ 96 + 98
Tính giá trị của biểu thức sau:
1/1 * 2 + 1/2 * 3 + .................... + 1/98 * 99 + 1/99 * 100
(1+2+3+...+98+99)*(2008*3+2008*2008*2)
Tính nhanh
a,(1+2 +3 +...+99) x (13 x 15 – 12 x 15 –15)
b,2+4+ 6+...+ 98+100–(1+3 +5 +...+97+99)
