Question

Ai giúp mình bài này với:

a) -5/9+ 3/5- 3/9+ -2/5

b) (1/9- 9/17)+ 3/6- (12/7- 1/2)+ 5/9

Answer 1

a) \(\left(-\dfrac{5}{9}\right)+\dfrac{3}{5}-\dfrac{3}{9}+\left(-\dfrac{2}{5}\right)\)

\(=\left[\left(-\dfrac{5}{9}\right)-\dfrac{3}{9}\right]+\left[\dfrac{3}{5}+\left(-\dfrac{2}{5}\right)\right]\)

\(=\left(-\dfrac{8}{9}\right)+\dfrac{1}{5}\)

\(=\left(-\dfrac{40}{45}\right)+\dfrac{9}{45}\)

\(=-\dfrac{31}{45}\)

b) \(\left(\dfrac{1}{9}-\dfrac{9}{17}\right)+\dfrac{3}{6}-\left(\dfrac{12}{7}-\dfrac{1}{2}\right)+\dfrac{5}{9}\)

\(=\dfrac{1}{9}-\dfrac{9}{17}+\dfrac{1}{2}-\dfrac{12}{7}+\dfrac{1}{2}+\dfrac{5}{9}\)

(nhóm các số cùng mẫu rồi làm tiếp)