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

ghi lại đoàn hoàn đc hăm :)?

Đôi khi t cảm thấy m không được bình thường :))

1200-31/40=47969/40

câu 2 =45/56+25/56=(45+25)/56=70/56=5/4

10/7+9/27+8/14+5/3

=10/7+1/3+4/7+5/3

=(10/7+4/7)+(1/3+5/3)

=14/7+6/3

=2+2

=4

câu hỏi gì khó thế. chẳng thấ quy luật nào car. bó tay. com.vn

a) \(\frac{7}{18}+\frac{4}{23}+\frac{11}{18}+\frac{19}{23}\)

\(=\left(\frac{7}{18}+\frac{11}{18}\right)+\left(\frac{4}{23}+\frac{19}{23}\right)\)

\(=1+1\)

\(=2\)

b) \(\frac{19}{15}+\frac{31}{23}-\frac{4}{15}-\frac{8}{23}\)

\(=\left(\frac{19}{15}-\frac{4}{15}\right)+\left(\frac{31}{23}-\frac{8}{23}\right)\)

\(=1+1\)

\(=2\)

ủng hộ tớ nha

a) (7/18+11/18)+(4/23+19/23)

=18/18+23/23

=1+1

=2

b)=2

`a: =(7/3-4/3)+11/5=16/5`

`b: =(18/13-5/13)+55/46=1+55/46=101/46`

`c: =27/25-4/9-2/25+5/9=(27/25-2/25)+(5/9-4/9)=1+1/9=10/9`

\(\dfrac{21}{16}\times\dfrac{8}{5}\times\dfrac{15}{7}=\dfrac{21\times8\times15}{16\times5\times7}=\dfrac{7\times3\times8\times5\times3}{8\times2\times5\times7}=\dfrac{3\times3}{2}=\dfrac{9}{2}\)

\(\dfrac{18}{9}\times\dfrac{9}{36}\times\dfrac{27}{3}=2\times\dfrac{1}{4}\times9=\dfrac{1}{2}\times9=\dfrac{9}{2}\)

    27 * 4 + 27 * 6

= 27 * ( 4 + 6 )

= 27 * 10

= 270

    73 * 2 + 73 * 8

= 73 * ( 2 + 8 )

= 73 * 10

= 730

27*4+27*6=27*(4+6)=27*10=270

73*2+73*8=73*(2+8)=73*10=730