[1-1/2]* [1-1/3] *[1-1/4] *[1-1/5]*[1-1/6]*[1-1/7]* [1-1/8]

2 câu trả lời

Ta có :

$\bigg(1-\dfrac{1}{2}\bigg). \bigg(1-\dfrac{1}{3}\bigg)....\bigg(1-\dfrac{1}{8}\bigg)$

$=\dfrac{1}{2}.\dfrac{2}{3}.\dfrac{3}{4}....\dfrac{7}{8} $

$=\dfrac{1.2.3.4.5.6.7}{2.3.4.5.6.7.8} $

$=\dfrac{1}{8} $

 

=1/2*2/3*3/4*4/5*5/6*6/7*7/8

=1*2*3*4*5*6*7/2*3*4*5*6*7*8

=1/8

Câu hỏi trong lớp Xem thêm