TL :
= 3 333 000
_HT_
S= 1x2 + 2x3 + 3x4 + 4x5 + ...+ 99x100
S x 3 = 1x2x3 + 2x3x3 + 3x4x3 + 4x5x3 + ... + 99x100x3
S x 3 = 1x2x3 + 2x3x(4-1) + 3x4x(5-2) + 4x5x(6-3) + ... + 99x100x(101-98)
S x 3 = 1x2x3 + 2x3x4 - 1x2x3 + 3x4x5 - 2x3x4 + 4x5x6 - 3x4x5 + ... + 99x100x101 - 98x99x100.
S x 3 = 99x100x101 A = 99x100x101 : 3 A = 333300
TL
=3333000
Hok tốt nhe bn
#Kirito
A = 1x2 + 2x3 + 3x4 + 4x5 + ...+ 99x100 +100x101
A x 3 = 1x2x3 + 2x3x3 + 3x4x3 + 4x5x3 + ... + 99x100x3 + 100x101x3
A x 3 = 1x2x3 + 2x3x(4-1) + 3x4x(5-2) + 4x5x(6-3) + ... + 99x100x(101-98) + 100x101x(102-99)
A x 3 = 1x2x3 + 2x3x4 - 1x2x3 + 3x4x5 - 2x3x4 + 4x5x6 - 3x4x5 + ... + 99x100x101 - 98x99x100 + 100x101x102 - 99x100x101
A x 3 = 100x101x102
A = 100x101x102 : 3 = 343400
Good luck ! =33
có phải lớp 6a1 ko
TL:
=3333000
HT
LAM
Đầu bafibn kia cho nhân tới 101 cơ mà, sao toàn nhân đến có 100 thế ??
bằng cái nịt bạn nhé