Ta có

\(A=\dfrac{19}{25}\left(\dfrac{3}{7}+\dfrac{25}{19}\right)-\dfrac{3}{7}\left(\dfrac{19}{25}-\dfrac{7}{3}\right)\\ A=\dfrac{19}{25}.\dfrac{3}{7}+\dfrac{19}{25}.\dfrac{25}{19}-\dfrac{3}{7}.\dfrac{19}{25}+\dfrac{3}{7}.\dfrac{7}{3}\\ A=\dfrac{19}{25}.\dfrac{3}{7}-\dfrac{19}{25}.\dfrac{3}{7}+\dfrac{25}{9}.\dfrac{19}{25}+\dfrac{3}{7}.\dfrac{7}{3}\\ A=0+1+1\\ A=2\)

Vậy A= 2

C

= -7/25 x ( 11/13 + 2/13 ) - 18/25

= - 7/25 x 1 - 18/25 

= -7/25 - 18/25 

= -1

nhớ tích cho mình nha mình cảm ơn rất nhìu^^

\(=\dfrac{-7}{25}\left(\dfrac{11}{13}+\dfrac{2}{13}\right)-\dfrac{18}{25}=-1\)

C=2

Xin phép đc ghi lại đề như sau \(C=\frac{19}{25}\left(\frac{3}{7}+\frac{25}{19}\right)-\frac{3}{7}\left(\frac{19}{25}-\frac{7}{3}\right)\)\(=\frac{19}{25}.\frac{3}{7}+\frac{19}{25}.\frac{25}{19}-\frac{3}{7}.\frac{19}{25}+\frac{3}{7}.\frac{7}{3}=\frac{19}{25}.\frac{3}{7}-\frac{3}{7}.\frac{19}{25}+\frac{19}{25}.\frac{25}{19}+\frac{3}{7}.\frac{7}{3}=0+1+1=2\)

\(9\frac{7}{25}+\frac{3}{25}\cdot\frac{7}{11}-\frac{7}{25}\cdot\frac{14}{11}\)

\(=9\frac{7}{25}+\frac{3}{25}\cdot\frac{7}{11}-\frac{14}{25}\cdot\frac{7}{11}\)

\(=9\frac{7}{25}+\frac{7}{11}\cdot\left(\frac{3}{25}-\frac{14}{25}\right)\)

\(=9\frac{7}{25}+\frac{7}{11}\cdot\left(-\frac{11}{25}\right)\)

\(=9\frac{7}{25}+\left(-\frac{7}{25}\right)\)

\(=9\)

Chắc sai =]]

thank

( -7/25 + -7/25 ) . ( 11/13 + 2/13 ) - 18/25

-14/25 . 1 - 18/25

= -32/25

=7/25.(11/13+2/13)- 18/25

=7/25.1-18/25

=7/25-18/25

=-11/25

\(=-\frac{7}{25}.\left(\frac{11}{13}+\frac{2}{13}\right)-\frac{18}{25}\)

\(=-\frac{7}{25}.1-\frac{18}{25}\)

\(=-\frac{7}{25}-\frac{18}{25}\)

\(=1\)

\(A=\frac{19}{25}.\left(\frac{3}{7}+\frac{25}{19}\right)-\frac{3}{7}.\left(\frac{19}{25}-\frac{7}{3}\right)\)

=> \(A=\frac{19}{25}.\frac{232}{133}-\frac{3}{7}.\frac{232}{75}\)

=> \(A=\frac{232}{175}-\frac{232}{175}\)

=> \(A=0\)

A =0 nha

A=0 nha