mới làm wen vs dạng này, chưa rõ lắm, mong các bạn chỉ giúp
tính:
Sn = 1.1! + 2.2! +... +n.n!
Su= 1[SUB2]2[/SUB2] - 2[SUB2]2[/SUB2] + 3[SUB2]2[/SUB2] - 4[SUB2]2[/SUB2] +...+ (-1)[SUB2]n-1[/SUB2]n[SUB2]2[/SUB2]
Sm = \[\frac{1^{2}}{1.3} + \frac{2^{2}}{3.5} + ... + \frac{n^{2}}{(2n-1)(2n+1)}\]
tính:
Sn = 1.1! + 2.2! +... +n.n!
Su= 1[SUB2]2[/SUB2] - 2[SUB2]2[/SUB2] + 3[SUB2]2[/SUB2] - 4[SUB2]2[/SUB2] +...+ (-1)[SUB2]n-1[/SUB2]n[SUB2]2[/SUB2]
Sm = \[\frac{1^{2}}{1.3} + \frac{2^{2}}{3.5} + ... + \frac{n^{2}}{(2n-1)(2n+1)}\]