\(\left(\frac{7}{19.31}+\frac{5}{19.43}+\frac{3}{23.43}+\frac{11}{23.57}\right):\left(\frac{1}{31}-\frac{1}{57}\right)\)

\(=\frac{7}{19}.\frac{7}{31}+\frac{5}{19}.\frac{5}{43}+\frac{3}{23}.\frac{3}{43}+\frac{11}{23}.\frac{11}{57}:\frac{1}{31}-\frac{1}{57}\)

\(=\frac{7}{19}+\frac{5}{19}.\frac{7}{31}+\frac{1}{31}:\frac{5}{43}-\frac{3}{43}.\frac{3}{23}+\frac{11}{23}.\frac{11}{57}+\frac{1}{57}\)

\(=\frac{12}{19}.\frac{8}{31}:\frac{2}{43}.\frac{7}{16}.\frac{4}{19}\)

\(=\frac{1204}{1767}\)

ko bít

Bai de vcl

A=4/7.31+6/7.41+9/10.41+7/10.57

A=20/35.31+30/35.31+45/50.41+35/50.57

A=5.(4/35.31+6/35.41+9/50.41+7/50.57)

=5.(1/31-1/35+1/35-1/41+1/41-1/50+1/50-1/57)

A=5.(1/31-1/57)

B=7/19.31+5/19.43+3/23.43+11/23.57

B=14/34.31+10/38.43+6/46.43+22/46.57

B=2.(7/34.31+5/38.43+3/46.43+11/46.57

B=2.(1/31-1/34+1/34-1/43+1/43-1/46+1/46-1/57)

B=2.(1/31-1/57)

    5.(1/31-1/57)

Vay A/B=5/2

dau /la phan so do