Question

tính hợp lý:

1, \(\dfrac{6}{13}\)- 2\(\dfrac{2}{5}\)+\(\dfrac{7}{13}\)+\(\dfrac{21}{15}\)-\(\dfrac{37}{38}\)

2, 4\(\dfrac{3}{8}\)- 7\(\dfrac{2}{3}\)+ 4\(\dfrac{1}{6}\)+\(\dfrac{1}{2}\)

giúp mik với, mik hứa tick

 

Answer 1

1: =(6/13+7/13)+(-2-2/5+7/5)-37/38

=2-1-1-37/38

=-37/38

2: \(=\dfrac{35}{8}-\dfrac{23}{3}+\dfrac{25}{6}+\dfrac{1}{2}\)

\(=\dfrac{35}{8}-\dfrac{46}{6}+\dfrac{25}{6}+\dfrac{3}{6}\)

=35/8-18/6

=35/8-3=11/8

Answer 2

\(1,\dfrac{6}{13}-2\dfrac{2}{5}+\dfrac{7}{13}+\dfrac{21}{15}-\dfrac{37}{38}=\left(\dfrac{6}{13}+\dfrac{7}{13}\right)+\left(\dfrac{-12}{5}+\dfrac{21}{15}\right)-\dfrac{37}{38}=1+\left(-1\right)-\dfrac{37}{38}=0-\dfrac{37}{38}=\dfrac{-37}{38}\)

\(2,4\dfrac{3}{8}-7\dfrac{2}{3}+4\dfrac{1}{6}+\dfrac{1}{2}=\dfrac{35}{8}-\dfrac{23}{3}+\dfrac{25}{6}+\dfrac{1}{2}=\left(\dfrac{35}{8}+\dfrac{1}{2}\right)+\left(\dfrac{25}{6}-\dfrac{23}{3}\right)=\left(\dfrac{35}{8}+\dfrac{4}{8}\right)+\left(\dfrac{25}{6}-\dfrac{46}{6}\right)=\dfrac{39}{8}+\dfrac{-7}{2}=\dfrac{39}{8}+\dfrac{-28}{8}=\dfrac{11}{8}\)