(17*8)+(51*4)=

136+204=340

340

tick cho mình nhé

=17x2x4+51x4

=34x4+51x4

=4x(34+51)

=4x85

=340 

các bạn cho mk vài li-ke cho tròn 770 với 

12/17+8/17=20/17+19/17=39/17

a) = \(\left(\dfrac{2}{7}+\dfrac{4}{7}+\dfrac{1}{7}\right):\dfrac{27}{31}\)

= \(\dfrac{7}{7}\) x \(\dfrac{31}{27}\)

= 1 x \(\dfrac{31}{27}\) = \(\dfrac{31}{27}\)

b) = \(\left(\dfrac{23}{45}:\dfrac{23}{45}\right)\)x \(\dfrac{17}{51}\)

= 1 x \(\dfrac{17}{51}\)= \(\dfrac{17}{51}\)

(13/17-5/17):8/3

=8/17:8/3

=3/17

=\(\dfrac{13}{17}:\dfrac{8}{3}-\dfrac{5}{17}:\dfrac{8}{3}\)

=\(\left(\dfrac{13}{17}-\dfrac{5}{17}\right):\dfrac{8}{3}\)

=\(\dfrac{8}{17}:\dfrac{8}{3}\)

\(=\dfrac{3}{17}\)

\(\dfrac{13}{17}:\dfrac{8}{3}-\dfrac{5}{17}:\dfrac{8}{3}=\dfrac{13}{17}.\dfrac{3}{8}-\dfrac{5}{17}.\dfrac{3}{8}=\dfrac{3}{8}\left(\dfrac{13}{17}-\dfrac{5}{17}\right)=\dfrac{3}{8}.\dfrac{8}{17}=\dfrac{3}{17}\)

39/17

39/17

  12/17 + 19/17 + 8/17

=         31/17 + 8/17

=            39/17

Vậy.... [kết luận]

\(=\dfrac{5}{12}+\left(\dfrac{8}{17}+\dfrac{60}{17}\right)\\ =\dfrac{5}{12}+4=4\dfrac{5}{12}\)

=512+(817+6017)=512+4=4512

5/12 + 8/17 + 60/17

= 5/12 + 68/7

= 5/12 + 4/1

= 5/12 + 48/12

= 53/12

HT

a) 19,17x25x4=19,17(25x4)=19,17x100=1917

b)1,79x(8x125)=1,79x1000=1790

chúc bạn học tốt

= (5/9 + 4/9) x 8/17

= 1 x 8/17

= 8/17

=(5/9+4/9).8/17

=1.8/17

=8/17

5/9 nhân 8/17+4/9 nhân 8/17

=[5/9+4/9] nhân 8/17

=1 nhân 8/17

8/17

a, \(\dfrac{12}{17}\) x \(\dfrac{21}{63}\) x \(\dfrac{51}{9}\)

=  \(\dfrac{3\times4}{17}\)  x \(\dfrac{3\times7}{9\times7}\) x \(\dfrac{17\times3}{9}\)

= \(\dfrac{4}{3}\)