( 1- \(\frac{1}{2}\))x( 1- \(\frac{1}{3}\))x( 1- \(\frac{1}{4}\))x( 1- \(\frac{1}{5}\))x( 1- \(\frac{1}{6}\)).

= \(\frac{1}{2}\)x \(\frac{2}{3}\)x \(\frac{3}{4}\)x \(\frac{4}{5}\)x \(\frac{5}{6}\).

= \(\frac{1\times2\times3\times4\times5}{2\times3\times4\times5\times6}\).

= \(\frac{1}{6}\).

Ăn có ...chơi có. ...

cảm ơn các bạn rất nhiều

nhớ là tính nhanh nha các bạn

chịu

\(\left(1-\frac{1}{2}\right)x\left(1-\frac{1}{3}\right)x\left(1-\frac{1}{4}\right)x\left(1-\frac{1}{5}\right)x\left(1-\frac{1}{6}\right)\)

\(=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}.\frac{4}{5}.\frac{5}{6}\)

\(=\frac{1.2.3.4.5}{2.3.4.5.6}=\frac{1}{6}\)

Phạm Tuấn Đạt làm đúng rồi đó

Mình cũng làm theo bạn ấy

1.a,=(54+45+1).113

=100.113

=11300

b,=(3/7+8/14)+(4/9+10/18)

=1+1

=2

2.a,=13/10+1/3

=49/30

b,=12/9.(1/12+1/6)

=12/9.1/4

=1/3

c,=3/4.3/2

=9/8

d,=3/2-1/3

=7/6

1:tính bằng cách thuận tiện nhất:

a)54 x 113 + 45 x 113 + 113

= 54 x 113 + 45 x 113 + 113x1

=113 x(54+45+1)

= 113x100

=1300

 b)3/7 + 4/9 + 8/14 + 10/18

=(3/7+8/14)+(4/9+10/18)

=    1           + 1

=2

\(\left(1-\frac{1}{2}\right)\left(1-\frac{1}{3}\right)\left(1-\frac{1}{4}\right)\left(1-\frac{1}{5}\right)\left(1-\frac{1}{6}\right)\)

\(=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}.\frac{4}{5}.\frac{5}{6}=\frac{1}{6}\)

\(=25\%+25\%\times38+25\%\times50+25\%\times11\)

\(=25\%\times\left(1+38+50+11\right)=25\%\times100=25\)

\(\dfrac{25}{100}+\dfrac{1}{4}\times38+25\%\times50+0,25\times11\)

\(0,25+0,25\times38+0,25\times50+0,25\times11+1\)

\(0,25\times\left(38+50+11+1\right)\)

\(0,25\times100\)

\(25\)

đáp án 1/6

Đặt A  = 1 - 1/2 + 1 - 1/6 + 1 - 1/12 + 1 - 1/20 + 1 - 1/30 + 1 - 1/42 + 1 - 1/56 + 1 - 1/72 + 1 - 1/89
=  (1 + 1 + 1 + .... 1 + 1) + (1/2 + 1/6 + 1/12 + 1/20 + 1/30 + 1/42 + 1/56 + 1/72 + 1/90)
= 9 - (1/1x2 + 1/2x3 + 1/3x4 + 1/4x5 + 1/5x6 + 1/6x7 + 1/7x8 + 1/8x9 + 1/9x10)
Mỗi phân số thành phần trong biểu thức () ta tách được như sau:
   1/1 x 2 = 1- 1/2
   1/2 x 3 = 1/2 - 1/3

 1/3 x 4 = 1/3 - 1/4
   ........
   1/9 x 10 = 1/9 - 1/10
Như vậy:
A  = 9 - (1-1/2 + 1/2-1/3 + 1/3-1/4 + 1/4-1/5 + 1/5-1/6 + 1/6-1/7 + 1/7-1/8 + 1/8-1/9 + 1/9-1/10)

  = 9 - (1 - 1/10)
    = 9 - 9/10
    = 81/10
                                               Đáp số: 81/10

\(\left(1-\frac{1}{2}\right)x\left(1-\frac{1}{3}\right)x\left(1-\frac{1}{4}\right)x\left(1-\frac{1}{5}\right)x\)\(\left(1-\frac{1}{6}\right)\)

=\(\frac{1}{2}x\frac{2}{3}x\frac{3}{4}x\frac{4}{5}x\frac{5}{6}\)

=\(\frac{1x2x3x4x5}{2x3x4x5x6}\)

=\(\frac{1}{6}\)

theo mình nghĩ là 

( 112 x 115 ) x ( 113 x 114 ) x 116 

sai thì cho xin lỗi nha bn

1/6

\(=\dfrac{1}{2}\cdot\dfrac{2}{3}\cdot\dfrac{3}{4}\cdot\dfrac{4}{5}\cdot\dfrac{5}{6}=\dfrac{1.2.3.4.5}{2.3.4.5.6}=\dfrac{1}{6}\)

\(\dfrac{1}{6}\)