A=1x4+4x7+7x10+.........+94x97
tìm A
Tính
3/1x4 + 3/4x7 + 3/7x10 + ... + 3/94x97
s=1/1x4+1/4x7+1/7x10+...+1/94x97+1/97x100
tnhs giá trị của B khi B =1x 4+4x7+7x10+10x13+......+91x94+94x97
2/1x4+2/4x7+...+2/97x100
2/1x4+2/4x7+....+2/97x100
1x4+2x5+3x6+4x7+....+98x101
1x4+4x7+7x10+7x13+...+97x101
C= 1x4+2x5+3x6+4x7+....+1006x1009 = ?