A =\(\frac{2\left(1-\frac{1}{19}+\frac{1}{43}-\frac{1}{1943}\right)}{3\left(1-\frac{1}{19}+\frac{1}{43}-\frac{1}{1943}\right)}:\frac{4\left(1-\frac{1}{29}+\frac{1}{41}-\frac{1}{2941}\right)}{5\left(1-\frac{1}{29}+\frac{1}{41}-\frac{1}{2941}\right)}\)

=\(\frac{2}{3}:\frac{4}{5}=\frac{2}{3}.\frac{5}{4}=\frac{10}{12}=\frac{5}{6}\)

\(A=\frac{2.\left(1-\frac{1}{19}+\frac{1}{43}-\frac{1}{1943}\right)}{3.\left(1-\frac{1}{19}+\frac{1}{43}-\frac{1}{1943}\right)}:\frac{4\left(1-\frac{1}{29}+\frac{1}{41}-\frac{1}{2941}\right)}{5.\left(1-\frac{1}{29}+\frac{1}{41}-\frac{1}{2941}\right)}=\frac{2}{3}:\frac{4}{5}=\frac{2}{3}.\frac{5}{4}=\frac{5}{6}\)

Xin lỗi nha, mình chỉ biết làm bài này nhõn bằng cách qui đồng nhưng số lớn lắm!

2-2/19+2/43-2/1943

3-3/19+3/43-3/1943

=2(1-1/19+1/43-1/1943) 

   3(1-1/19+1/43-1/1943)

=2/3

Chúc bạn học tốt!!!!!

\(1-\frac{\frac{2}{19}+\frac{2}{43}-\frac{2}{2013}}{\frac{3}{19}+\frac{3}{43}-\frac{3}{2013}}\)= \(1-\frac{2\left(\frac{1}{19}+\frac{1}{43}-\frac{1}{2013}\right)}{3\left(\frac{1}{19}+\frac{1}{43}-\frac{1}{2013}\right)}\)= 1 - \(\frac{2}{3}\)=\(\frac{1}{3}\)

\(1-\frac{\frac{2}{19}+\frac{2}{43}-\frac{2}{2013}}{\frac{3}{19}+\frac{3}{43}-\frac{3}{2013}}=1-\frac{2\left(\frac{1}{19}+\frac{1}{43}-\frac{1}{2013}\right)}{3\left(\frac{1}{19}+\frac{1}{43}-\frac{1}{2013}\right)}\)=\(1-\frac{2}{3}=\frac{1}{3}\)

\(A=\frac{2-\frac{2}{19}+\frac{2}{43}-\frac{2}{1995}}{3-\frac{3}{19}+\frac{3}{43}-\frac{3}{1995}}:\frac{4-\frac{4}{29}+\frac{4}{41}-\frac{4}{2941}}{5-\frac{5}{29}+\frac{5}{41}-\frac{5}{2941}}\)

\(\Rightarrow A=\frac{2\left(1-\frac{1}{19}+\frac{1}{43}-\frac{1}{1995}\right)}{3\left(1-\frac{1}{19}+\frac{1}{43}-\frac{1}{1995}\right)}:\frac{4\left(1-\frac{1}{29}+\frac{1}{41}-\frac{1}{2941}\right)}{5\left(1-\frac{1}{29}+\frac{1}{41}-\frac{1}{2941}\right)}\)

\(\Rightarrow A=\frac{2}{3}:\frac{4}{5}\)

\(\Rightarrow A=\frac{2}{3}.\frac{5}{4}\)

\(\Rightarrow A=\frac{10}{12}=\frac{5}{6}\)

thanks bạn

5/6 day 

Giúp Mik ik mai nộp oy

\(3\frac{14}{19}+\frac{13}{17}+\frac{35}{43}+6\frac{5}{19}+\frac{8}{43}\)

\(=3+6+\left(\frac{14}{19}+\frac{5}{19}\right)+\left(\frac{35}{43}+\frac{8}{43}\right)+\frac{13}{17}\)

\(=9+1+1+\frac{13}{17}\)

\(=11+\frac{13}{17}\)

\(=\frac{200}{17}\)

\(3\frac{14}{19}+\frac{13}{17}+\frac{35}{43}+6\)

\(=\frac{71}{19}+\frac{13}{17}+\frac{35}{43}+6\)

\(=\frac{1454}{323}+\frac{35}{43}+6\)

\(=5,...+6\)

\(=11,...\)

\(Bai2a\)\(A=\frac{\sqrt{3}-\sqrt{6}}{1-\sqrt{2}}-\frac{2+\sqrt{8}}{1+\sqrt{2}}\)

\(=\frac{\sqrt{3}\left(1-\sqrt{2}\right)}{1-\sqrt{2}}-\frac{2\left(1+\sqrt{2}\right)}{1+\sqrt{2}}\)

\(=\sqrt{3}-2\) 

\(VayA=\sqrt{3}-2\)