Tinh nhanh
g ) .
\(=10\dfrac{2}{9}+2\dfrac{2}{5}-7\dfrac{2}{9}=\left(10\dfrac{2}{9}-7\dfrac{2}{9}\right)+2\dfrac{2}{5}\)
\(=\left(\left(10-7\right)\left(\dfrac{2}{9}-\dfrac{2}{9}\right)\right)+\dfrac{12}{5}\)
\(=3+\dfrac{12}{5}=\dfrac{15}{5}+\dfrac{12}{5}=\dfrac{27}{5}\)
h ) .
\(=6\dfrac{3}{10}-3\dfrac{4}{7}-2\dfrac{3}{10}=\left(6\dfrac{3}{10}-2\dfrac{3}{10}\right)-3\dfrac{4}{7}\)
\(=\left(\left(6-2\right)\left(\dfrac{3}{10}-\dfrac{3}{10}\right)\right)-\dfrac{25}{7}\)
\(=4-\dfrac{25}{7}=\dfrac{28}{7}-\dfrac{25}{7}=\dfrac{3}{7}\)
g,92/9+12/5-65/9
=(92/9-65/9)+12/5
=3+12/5
=15/5+12/5
=27/5
h,=63/10-25/7-23/10
=(63/10-23/10)-25/7
=4-25/7
=28/7-25/7
=3/7
i,=67/9+51/11-31/9
=(67/9-31/9)+51/11
=4+55/11
=44/11+55/11
=99/11
=9
i) .
\(=7\dfrac{4}{9}+4\dfrac{7}{11}-3\dfrac{4}{9}=\left(7\dfrac{4}{9}-3\dfrac{4}{9}\right)-4\dfrac{7}{11}\)
\(=\left(\left(7-3\right)\left(\dfrac{4}{9}-\dfrac{4}{9}\right)\right)-\dfrac{51}{11}\)
\(=4-\dfrac{51}{11}=\dfrac{44}{11}-\dfrac{51}{11}=-\dfrac{7}{11}\)
g) \(10\dfrac{2}{9}+\left(2\dfrac{2}{5}-7\dfrac{2}{9}\right)\)
\(=10\dfrac{2}{9}+\left(-5\right)\dfrac{8}{45}\)
\(=\left[\left(10+\left(-5\right)\right)\left(\dfrac{2}{9}+\dfrac{8}{45}\right)\right]\)
\(=5\dfrac{2}{5}\)
\(=\dfrac{27}{5}\)
g =\(10\dfrac{2}{9}+2\dfrac{2}{5}-7\dfrac{2}{9}=\left(10\dfrac{2}{9}-7\dfrac{2}{9}\right)+2\dfrac{5}{9}=3+2\dfrac{2}{5}=\dfrac{15}{5}+\dfrac{12}{5}=\dfrac{27}{5}\)
i,=67/9+51/11-31/9=(67/9-31/9)+51/11=36/9+51/11=4-51/11=44/11-51/11=-7/11
g,92/9+12/5-65/9
=(92/9-65/9)+12/5
=3+12/5
=15/5+12/5
=27/5=5 2/5
h,=63/10-25/7-23/10
=(63/10-23/10)-25/7
=4-25/7
=28/7-25/7
=3/7
i,=67/9+51/11-31/9
=(67/9-31/9)+51/11
=4+55/11
=44/11+55/11
=99/11
=9
Tinh nhanh:
TINH NHANH
