1+1x1-1x1x1-1x1-1x1-1=....................?
S1=1x1
S2=2x2-1x1
S3=3x3-(2x2-1x1)
S4=4x4-(3x3-(2x2-1x1))
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a)Hãy viết dãy số S5
b)Nếu dãy số này cứ tiếp tục như thế thì S2011 có giá trị là bao nhiêu?
A=1x2+2x3+3x4+...+49x50
B=1x3+3x5+5x7+...+99x101
C=1x2x3+2x3x4+3x4x5+...+50x51x52
D=1x4+2x5+3x6+...+60x63
E=1x1+2x2+3x3+...+50x50
F=1x1+3x3+5x5+...+71x71
G=1x1+4x4+7x7+...+100x100
I=1x2x3+3x4x5+5x6x7+...+69x70x71
1x1=?
1x1+3x3+5x5+...+25x25=
[1x1]x....x[99x100]=?
1x1!+2x2!+3x3!+4x4!+...+100x100!
1x1!+2x2!+3x3!+4x4!+...+100x100! = ?
A=1x1+2x2+3x3+...+100x100