Question

[Người Bí Mật]

1, Tính nhanh (nếu có thể):

a, (\(\dfrac{1}{2}\)-\(\dfrac{7}{13}\)-\(\dfrac{1}{3}\))+(\(\dfrac{-6}{13}\)+\(\dfrac{1}{3}\)+1\(\dfrac{1}{3}\))

b, 0.75+\(\dfrac{2}{5}\)+(\(\dfrac{1}{9}\)-1\(\dfrac{2}{5}\)+\(\dfrac{5}{4}\))

c, (-1\(\dfrac{1}{2}\):\(\dfrac{3}{4}\)).(-4\(\dfrac{1}{2}\))-\(\dfrac{1}{2}\)

2, Tìm x biết: x.(x-\(\dfrac{2}{3}\))=0

Answer 1

[Nguyễn Lê Phước Thịnh]

Bài 1:

a: \(=\dfrac{1}{2}-\dfrac{7}{13}-\dfrac{1}{3}-\dfrac{6}{13}+\dfrac{1}{3}+\dfrac{4}{3}=\dfrac{4}{3}-1+\dfrac{1}{2}=\dfrac{1}{3}+\dfrac{1}{2}=\dfrac{5}{6}\)

b: \(=\dfrac{3}{4}+\dfrac{2}{5}+\dfrac{1}{9}-1-\dfrac{2}{5}+\dfrac{5}{4}=2-1+\dfrac{1}{9}=\dfrac{10}{9}\)

c: \(=\left(\dfrac{-3}{2}\cdot\dfrac{4}{3}\right)\cdot\dfrac{-9}{2}-\dfrac{1}{2}=9-\dfrac{1}{2}=8.5\)