(1-1/2x1/2)x(1-1/3x1/3)x(1-1/4x1/4)x…x(1-1/2007x1/2007) = ( 1 - 1/4 ) x ( 1 - 1/9 ) x ( 1- 1/16) x .....x ( 1 - 1/4028049) = 3/4 x 8/9 x 15/16 x .....x 4028048 / 4028049 = 3 x 8 x 15 x .....x 4028048 / 4 x 9 x 16 x ......x 4028049 = 1 x 3 x 2 x 4 x 3 x 5 x .....x 2006 x 2008 / 2x2 x 3 x3 x 4 x 4 x .....x 2007 x 2007 = ( 1 x 2 x 3 x .....x 2006) x ( 3 x 4 x 5 x .....x 2008) / ( 2 x 3 x 4 x ....x 2007) x ( 2 x 3 x 4 x ....x 2007) = 2008 / 2007 x 2 = 1004 / 2007

(1-1/2x1/2)x(1-1/3x1/3)x(1-1/4x1/4)x…x(1-1/2007x1/2007)
= ( 1 - 1/4 ) x ( 1 - 1/9 ) x ( 1- 1/16) x .....x ( 1 - 1/4028049)
= 3/4 x 8/9 x 15/16 x .....x 4028048 / 4028049
= 3 x 8 x 15 x .....x 4028048 / 4 x 9 x 16 x ......x 4028049
= 1 x 3 x 2 x 4 x 3 x 5 x .....x 2006 x 2008 / 2x2 x 3 x3 x 4 x 4 x .....x 2007 x 2007
= ( 1 x 2 x 3 x .....x 2006) x ( 3 x 4 x 5 x .....x 2008) / ( 2 x 3 x 4 x ....x 2007) x ( 2 x 3 x 4 x ....x 2007)
= 2008 / 2007 x 2
= 1004 / 2007

cách tính : bạn tính trong từng ngoặc tròn trc nhé. rồi bạn tính như bth thôi ạ!

= ( 2/15 - 4/9 ) : ( 1/3 + 4/15 )

= -14/45 : 3/5

= -14/27

a) 2/9 : 2/3 x 1/2

= 2/9 x 3/2 x 1/2

= 6/18 x 1/2

= 6/36

b) 2 + 1/4 x 4/3

= 2 + 4/7

= 2/1₍₇₎ + 4/7

= 14/7 + 4/7

= 18/7

c) 3 x 1/2 x 1/4

= 3/1 x 1/2 x 1/4

= 3/2 x 1/4

= 3/8

#Hok_tốt

Thông báo,Te2qAMq.png (1280×800)

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Tính 

a ) 5/2 x 1/3 + 1/4

= 5/5+1/4

=13/12

b)5/2 +  1/3 x 1/4

= 5/2 + 1/12

= 31/12

c ) 5/2 -1/3 :1/4

= 5/2  - 4/3

= 7/6

tk mk nha ( nếu đúng )

hihi mơn nha !!!!!!!!!!

a. = (5/2x2/3) +1/4

    = 5/3+1/4= 23/12

b. = 5/2+( 1/3x1/4)

    = 5/2+1/12

    =31/12

c. =5/2-( 1/3:1/4)

    = 5/2-4/3

    = 7/6

A, 5/2×1/3+1/4

  =5/6+1/4

  =13/12

B, 5/2+1/3×1/4

  =5/2+1/12

  =5/2—1/3:1/4

  =5/2—4/3

  =7/6

k mk nha

=

C, 5/2

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

= \(\frac{1}{2}\)- \(\frac{1}{12}\)

= \(\frac{6}{12}\)- \(\frac{1}{12}\)

= \(\frac{5}{12}\)

tk nhé

5

12

 kb và k nha

1/2-1/3x1/4=1/24

k cho mình nhé

a) \(\dfrac{11}{3}-\dfrac{2}{3}\times\dfrac{5}{6}\)

\(=\dfrac{11}{3}-\dfrac{10}{18}\)

\(=\dfrac{11}{3}-\dfrac{5}{9}\)

\(=\dfrac{33}{9}-\dfrac{5}{9}\)

\(=\dfrac{28}{9}\)

b) \(\dfrac{13}{2}+\dfrac{7}{6}:\dfrac{2}{3}\)

\(=\dfrac{13}{2}+\dfrac{7}{6}\cdot\dfrac{3}{2}\)

\(=\dfrac{13}{2}+\dfrac{7}{4}\)

\(=\dfrac{26}{4}+\dfrac{7}{4}\)

\(=\dfrac{33}{4}\)

c) \(\dfrac{28}{9}-\dfrac{3}{4}+\dfrac{1}{3}\)

\(=\dfrac{28}{9}+\dfrac{3}{9}-\dfrac{3}{4}\)

\(=\dfrac{31}{9}-\dfrac{3}{4}\)

\(=\dfrac{124}{36}-\dfrac{27}{36}\)

\(=\dfrac{97}{36}\)

d) \(\dfrac{5}{8}:\dfrac{2}{3}\times\dfrac{1}{5}\)

\(=\dfrac{5}{8}\times\dfrac{3}{2}\times\dfrac{1}{5}\)

\(=\dfrac{15}{80}\)

\(=\dfrac{3}{16}\)

a) \(\dfrac{11}{3}-\dfrac{2}{3}\times\dfrac{5}{6}=\dfrac{11}{3}-\dfrac{5}{9}=\dfrac{28}{9}\)

b) \(\dfrac{13}{2}+\dfrac{7}{6}:\dfrac{2}{3}=\dfrac{13}{2}+\dfrac{7}{6}\times\dfrac{3}{2}=\dfrac{13}{2}+\dfrac{7}{4}=\dfrac{33}{4}\)

c) \(\dfrac{28}{9}-\dfrac{3}{4}+\dfrac{1}{3}=\dfrac{97}{36}\)

d) \(\dfrac{5}{8}:\dfrac{2}{3}\times\dfrac{1}{5}=\dfrac{5}{8}\times\dfrac{3}{2}\times\dfrac{1}{5}=\dfrac{3}{16}\)

a) \(\dfrac{11}{3}-\dfrac{2}{3}\times\dfrac{5}{6}\)

\(=\dfrac{11}{3}-\dfrac{5}{9}\)

\(=\dfrac{33}{9}-\dfrac{5}{9}\)

\(=\dfrac{28}{9}\)

b) \(\dfrac{13}{2}+\dfrac{7}{6}:\dfrac{2}{3}\)

\(=\dfrac{13}{2}+\dfrac{7}{6}\times\dfrac{3}{2}\)

\(=\dfrac{13}{2}+\dfrac{7}{4}\)

\(=\dfrac{26}{4}+\dfrac{7}{4}\)

\(=\dfrac{33}{4}\)

c) \(\dfrac{28}{9}-\dfrac{3}{4}+\dfrac{1}{3}\)

\(=\dfrac{28}{9}+\dfrac{3}{9}-\dfrac{3}{4}\)

\(=\dfrac{31}{9}-\dfrac{3}{4}\)

\(=\dfrac{124}{36}-\dfrac{27}{36}\)

\(=\dfrac{97}{36}\)

d) \(\dfrac{5}{8}:\dfrac{2}{3}\times\dfrac{1}{5}\)

\(=\dfrac{5}{8}\times\dfrac{3}{2}\times\dfrac{1}{5}\)

\(=\dfrac{3}{16}\)

\(\dfrac{1}{2}+\dfrac{4}{3}\times\dfrac{1}{6}=\dfrac{1}{2}+\dfrac{4}{18}=\dfrac{9}{18}+\dfrac{4}{18}=\dfrac{13}{18}\)

1/2 + 2/9 = 13/18

13/18