dễ ẹc!!!!!!!!

=\(\frac{-278}{255}\)

a,-5/9 + 8/18 + -2/11 + 4/-9 + 7/15                                            b,5/17 + -9/15 + -2/17 + 2/5 + 14/17

= -5/9 + 4/9 + -2/+ 4/-9 + 7/15                                                 = 5/17 + -3/5 + -2/17 + 2/5 + 14/17

=(-5/9 + 4/9 + -4/9 ) +-2/11 + 7/15                                            = ( 5/17 + -2/17 + 14/17) + ( 2/5 + -3/5)

= -1/3 + -2/11 + 7/15                                                               =1 + -1/5

=-75/225 + -30/ 225 + 77/225                                                  =4/5              

= -25/225 = -1/9                                                                        ( 4/5 = 0.8 )

a) 3/7 + 4/9 + 4/7 + 5/9

= ( 3/7 + 4/7 ) + ( 4/9 + 5/9 )

= 7/7 + 9/9

= 1  + 1 

= 2

b)1/5 + 4/10 + 9/15 + 16/20 + 25/25 + 36/30 + 49/35 + 64/40 + 81/45

= 1/5 + 2/5 + 3/5 + 4/5 + 5/5 + 6/5 + 7/5 + 8/5 + 9/5

= ( 1/5 + 9/5 ) + ( 2/5 + 8/5 ) + (7/5 + 3/5 ) + ( 4/5 + 6/5  ) + 5/5

= 2 + 2 + 2 + 2 + 1

= 2  x 4 + 1

= 8  +1 

= 9

c)  1/8 + 1/12 + 3/8 + 5/12

= ( 1/8 + 3/8 ) + ( 1/12 + 5/12)

= 4/8 + 6/12

= 1/2 + 1/2

= 2/4 = 1/2

mỏi tay rồi

d; (1 - \(\dfrac{1}{2}\)) x (1 - \(\dfrac{1}{3}\)) x (1 - \(\dfrac{1}{4}\)) x ... x ( 1 - \(\dfrac{1}{100}\))

 = \(\dfrac{1}{2}\) x \(\dfrac{2}{3}\)  x \(\dfrac{3}{4}\) x \(\dfrac{3}{4}\) x ... x \(\dfrac{99}{100}\)

= \(\dfrac{1}{100}\)

e; \(\dfrac{9}{5}\) : \(\dfrac{17}{15}\) + \(\dfrac{8}{5}\) : \(\dfrac{17}{15}\)

=  \(\dfrac{9}{5}\) x \(\dfrac{15}{17}\) + \(\dfrac{8}{5}\) x \(\dfrac{15}{17}\)

=  \(\dfrac{27}{17}\) + \(\dfrac{24}{17}\)

=  \(\dfrac{51}{17}\)

=   3

3

bấm máy tính là ra thui

mình biết rồi các bạn hãy nhanh tay lên nhá

(9/5 + 8/5) : 17/15 = 17/5 :17/15 = 3

ai gioi hon tui

1)     \(\frac{1}{5}+\frac{3}{17}-\frac{4}{3}+\left(\frac{4}{5}-\frac{3}{17}+\frac{1}{15}\right)\)

\(=\frac{1}{5}+\frac{3}{17}-\frac{4}{3}+\frac{4}{5}-\frac{3}{17}+\frac{1}{15}\)

\(=\left(\frac{1}{5}+\frac{4}{5}\right)+\left(\frac{3}{17}-\frac{3}{17}\right)-\left(\frac{4}{3}-\frac{1}{15}\right)\)

\(=1+0-\frac{19}{15}\)

\(=-\frac{14}{15}\)

MÌNH

NHẦM

CHÚT

NHA

KẾT QUẢ CUỐI CÙNG LÀ:

\(-\frac{4}{15}\)

sorry!!!

còn câu 2

= 17/15 : ( 9/5 + 8,5 )

=  17/15 :17/5

= 1/3

\(\dfrac{9}{5}:\dfrac{17}{15}+\dfrac{8}{5}:\dfrac{17}{15}=\dfrac{9}{5}\times\dfrac{15}{17}+\dfrac{8}{5}\times\dfrac{15}{17}=\dfrac{15}{17}\times\left(\dfrac{9}{5}+\dfrac{8}{5}\right)=\dfrac{15}{17}\times\dfrac{17}{5}=\dfrac{255}{85}=3\)

9/5 : 17/15 + 8/5 : 17/15= 17/15 : ( 9/5 + 8,5 )

                                      =  17/15 :    17/5

                                      =      1/3

a) 27 + ( -2019 ) + ( -27 )

= [ 27 + ( - 27) ] + ( - 2019)

= 0 - 2019

= - 2019

b) ( -10 ) + 23 + ( -20 ) + 30

= [ ( - 10 ) + (- 20) + 30]+ 23

= [ ( - 30) + 30] + 23

= 0 + 23 = 23

c) ( -2 ).125.( -5 ).( -8 ).( +17 )

= [ - 2 . ( - 5 )] . [ 125 . ( - 8)] . 17

= 10 . 1000 . 17

= 170000

d) ( -9 ) + ( -15 ) + ( -33 )

= - 24 + ( - 33 )

= - 57

e) ( -15 ).6 = - 80

f) 5.( -9 ) + 4.9 = 9 . ( - 5 + 4) = 9 . 1 = 9

= 51/17

sao lai ra 51/17 vay ban

      \(\frac{9}{5}:\frac{17}{15}+\frac{8}{5}:\frac{17}{15}\)

\(=\frac{17}{15}:\left(\frac{9+8}{5}\right)\)

\(=\frac{17}{15}:\frac{17}{5}\)

\(=\frac{17}{15}X\frac{5}{17}\)

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

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