[Toán 8] Phép trừ phân thức đại số

V

vansang02121998

khó quá. ai giỏi toán help giùm mình
TÍNH NHANH:
[TEX]\frac{1}{x(x+1)}+\frac{1}{(x+1)(x+2)}+\frac{1}{(x+2)(x+3)}+\frac{1}{(x+3)(x+4)}+\frac{1}{(x+4)(x+5)}+\frac{1}{(x+5)(x+6)}[/TEX]


[TEX]\frac{1}{x(x+1)}+\frac{1}{(x+1)(x+2)}+\frac{1}{(x+2)(x+3)}+\frac{1}{(x+3)(x+4)}+\frac{1}{(x+4)(x+5)}+\frac{1}{(x+5)(x+6)}[/TEX]

[TEX]\frac{1}{x}-\frac{1}{x+1}+\frac{1}{x+1}-\frac{1}{x+2}+......-\frac{1}{x+6}[/tex]

[tex]\frac{1}{x}-\frac{1}{x+6}[/tex]

[tex]\frac{6}{x(x+6)}[/tex]
 
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