= 0.5 :0.5 -0.25:0.25+0.2:0.2 -0.125:0.125

= 1-1+1-1

=0+ 0

=0 

28,37-23,18-16,82+71,63
=(28,37+71,63)-(23,18+16,82)

=60

B=1/1x6 + 1/6x11 + 1/16x21 + 1/21x26 + 1/26x31

=1-1/6+1/6-1/11+1/11-....-1/31

=1-1/31=30/31

a) A = \(\left(28,37+71,63\right)-\left(23,18+16,82\right)\)

= 100 - 40

= 60

b) \(B=\dfrac{1}{1.6}+\dfrac{1}{6.11}+\dfrac{1}{11.16}+\dfrac{1}{16.21}+\dfrac{1}{21.26}+\dfrac{1}{26.31}\)

= \(\dfrac{1}{5}\left(\dfrac{5}{1.6}+\dfrac{5}{6.11}+...+\dfrac{5}{26.31}\right)\)

= \(\dfrac{1}{5}\left(1-\dfrac{1}{6}+\dfrac{1}{6}-\dfrac{1}{11}+...+\dfrac{1}{26}-\dfrac{1}{31}\right)\)

= \(\dfrac{1}{5}\left(1-\dfrac{1}{31}\right)=\dfrac{1}{5}.\dfrac{30}{31}=\dfrac{6}{31}\)

28,37-23,18-16,82+71,63 

= (28,37 + 71,63) - (23,18 + 16,82)

= 110 - 40

= 70

Chúc bạn học tôt.

( 99 + 1 ) x 2341
= 100 x 2341
= 234100

HT + :)))

\(\dfrac{1}{6}+\dfrac{1}{12}+\dfrac{1}{20}+\dfrac{1}{30}\)

\(=\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{6}\)

\(=\dfrac{1}{2}-\dfrac{1}{6}\)

\(=\dfrac{1}{3}\)

=1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6

=1/2-1/6=1/3

\(\dfrac{1}{2\times3}+\dfrac{1}{3\times4}+\dfrac{1}{4\times5}+\dfrac{1}{5\times6}=\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{6}=\dfrac{1}{2}-\dfrac{1}{6}=\dfrac{3-1}{6}=\dfrac{2}{6}=\dfrac{1}{3}\)

1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6

=1/2-1/6

=3/6-1/6

=2/6=1/3

= (1x1x1x1x1) -  = 1- =

Đề kiểu j vậy?

=1/2-1/3+1/3-1/4+...+1/6-1/7

=1/2-1/7

=5/14

(2/3+1/3):1/2

= 1 : 1/2

=1/2

học tốt  nhé !

2/3 : 1/2 + 1/3 : 1/2

= (2/3 + 1/3) : 1/2

=        1         : 1/2

=        1        x 2/1

=   2

\(\dfrac{1}{4}\) : 0,25 - \(\dfrac{1}{8}\) : 0,125 + \(\dfrac{1}{2}\) : 0,5 - 1

= 0,25 x 4 - 0,125 x 8 + 0,5 x 2 - 1

= 1 - 1 + 1 - 1

= 0 + 1 - 1

= 1 - 1

= 0

A = \(\dfrac{1}{4}\) : 0,25 - \(\dfrac{1}{8}\): 0,125 + \(\dfrac{1}{2}\): 0,5 - 1

A = \(\dfrac{1}{4}\) x 4 - \(\dfrac{1}{8}\) x 8 + \(\dfrac{1}{2}\) x 2 - 1

A = 1 - 1 + 1  - 1

A =  (1 - 1) + (1 - 1)

A = 0