Question

[Phan Ngọc Gia Hân]

Thực hiện phép tính hợp lí nếu có thể:

a)       4/5 x 11/7 - 4/5 x 1/7

b) 7/13 x 25/6 - 7/13 x -1/6

c) 4/13 x 5/11 + 4/13 x 6/11 - 4/13

giúp mình với, mình cần gấp

Answer 1

[Citii?]

a) \(\dfrac{4}{5}\times\dfrac{11}{7}-\dfrac{4}{5}\times\dfrac{1}{7}\)

\(=\dfrac{4}{5}\times\left(\dfrac{11}{7}-\dfrac{1}{7}\right)\)

\(=\dfrac{4}{5}\times\dfrac{10}{7}\)

\(=\dfrac{4}{1}\times\dfrac{2}{7}\)

\(=\dfrac{8}{7}\)

b) \(\dfrac{7}{13}\times\dfrac{25}{6}-\dfrac{7}{13}\times\dfrac{-1}{6}\)

\(=\dfrac{7}{13}\times\left(\dfrac{25}{6}-\dfrac{-1}{6}\right)\)

\(=\dfrac{7}{13}\times\dfrac{26}{6}\)

\(=\dfrac{7}{1}\times\dfrac{2}{6}\)

\(=\dfrac{14}{6}=\dfrac{7}{3}\)

c) \(\dfrac{4}{13}\times\dfrac{5}{11}+\dfrac{4}{13}\times\dfrac{6}{11}-\dfrac{4}{13}\)

\(=\dfrac{4}{13}\times\left(\dfrac{5}{11}+\dfrac{6}{11}\right)-\dfrac{4}{13}\)

\(=\dfrac{4}{13}\times\dfrac{11}{11}-\dfrac{4}{13}\)

\(=\dfrac{4}{13}\times\dfrac{11}{11}-\dfrac{4}{13}\times\dfrac{11}{11}\)

\(=\dfrac{4}{3}\times\left(\dfrac{11}{11}-\dfrac{11}{11}\right)\)

\(=\dfrac{4}{3}\times0=0\)

Answer 2

[Trần Nguyễn Phương Thảo]

a)\(\dfrac{4}{5}\cdot\dfrac{11}{7}-\dfrac{4}{5}\cdot\dfrac{1}{7}=\dfrac{4}{5}.\left(\dfrac{11}{7}-\dfrac{1}{7}\right)=\dfrac{4}{5}.\left(\dfrac{11-1}{7}\right)=\dfrac{4}{5}\cdot\dfrac{10}{7}=4\cdot\dfrac{2}{7}=\dfrac{8}{7}\)

b)\(\dfrac{7}{13}\cdot\dfrac{25}{6}-\dfrac{7}{13}\cdot\dfrac{-1}{6}=\dfrac{7}{13}\cdot\left(\dfrac{25}{6}-\dfrac{-1}{6}\right)=\dfrac{7}{13}\cdot\left(\dfrac{25}{6}+\dfrac{1}{6}\right)=\dfrac{7}{13}\cdot\dfrac{26}{6}=\dfrac{7}{13}\cdot\dfrac{13}{3}=\dfrac{7}{3}\)

c)

\(\dfrac{4}{13}\cdot\dfrac{5}{11}+\dfrac{4}{13}\cdot\dfrac{6}{11}-\dfrac{4}{13}=\dfrac{4}{13}.\left(\dfrac{5}{11}+\dfrac{6}{11}-1\right)=\dfrac{4}{13}\cdot\left(1-1\right)=\dfrac{4}{13}\cdot0=0\)