Question

[Nguyễn Thị Trà]

Thực hiện phép tính:

a) \(\dfrac{3}{4}\)+\(\dfrac{1}{4}\) x ( 1,25 - \(\dfrac{3}{4}\) ) : \(\dfrac{5}{8}\)

b) 1\(\dfrac{1}{3}\) x 0,75 - 4\(\dfrac{1}{2}\) : - 1\(\dfrac{4}{5}\) + - 0,5

c) ( \(\dfrac{3}{8}\)+\(\dfrac{-3}{4}\)+\(\dfrac{7}{12}\)) : \(\dfrac{5}{6}\)+\(\dfrac{1}{2}\)

d) 1\(\dfrac{1}{3}\) x (0,5) + (\(\dfrac{8}{15}\) - \(\dfrac{19}{30}\)) : \(\dfrac{6}{15}\)

e) 3,21 x (\(\dfrac{1}{2}\) - 2,5) + 28,8 : ( -1,3)

f) -1,25 x (\(\dfrac{3}{2}\) - 0,75) + 3,5 : ( -1,4)

Answer 1

[Nguyễn Lê Phước Thịnh]

a: \(\dfrac{3}{4}+\dfrac{1}{4}\left(1,25-\dfrac{3}{4}\right):\dfrac{5}{8}\)

\(=\dfrac{3}{4}+\dfrac{1}{4}\cdot\dfrac{2}{4}:\dfrac{5}{8}\)

\(=\dfrac{3}{4}+\dfrac{1}{4}\cdot\dfrac{1}{2}\cdot\dfrac{8}{5}=\dfrac{3}{4}+\dfrac{1}{5}=\dfrac{19}{20}\)

b: \(1\dfrac{1}{3}\cdot0,75-4\dfrac{1}{2}:\left(-1\dfrac{4}{5}\right)+\left(-0,5\right)\)

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

\(=1-\dfrac{1}{2}+\dfrac{9}{2}\cdot\dfrac{5}{9}=\dfrac{1}{2}+\dfrac{5}{2}=3\)

c: \(\left(\dfrac{3}{8}+\dfrac{-3}{4}+\dfrac{7}{12}\right):\dfrac{5}{6}+\dfrac{1}{2}\)

\(=\left(\dfrac{9}{24}-\dfrac{18}{24}+\dfrac{14}{24}\right)\cdot\dfrac{6}{5}+\dfrac{1}{2}\)

\(=\dfrac{5}{24}\cdot\dfrac{6}{5}+\dfrac{1}{2}=\dfrac{1}{4}+\dfrac{1}{2}=\dfrac{3}{4}\)

d: \(1\dfrac{1}{3}\cdot0,5+\left(\dfrac{8}{15}-\dfrac{19}{30}\right):\dfrac{6}{15}\)

\(=\dfrac{4}{3}\cdot\dfrac{1}{2}+\dfrac{-3}{30}:\dfrac{2}{5}\)

\(=\dfrac{2}{3}-\dfrac{1}{10}\cdot\dfrac{5}{2}=\dfrac{2}{3}-\dfrac{1}{4}=\dfrac{5}{12}\)

e: \(3,21\left(\dfrac{1}{2}-2.5\right)+28,8:\left(-1,3\right)\)

\(=3,21\cdot\left(-2\right)-\dfrac{288}{13}\)

\(=-6,42-\dfrac{288}{13}=-\dfrac{18573}{650}\)

f: \(-1,25\left(\dfrac{3}{2}-0,75\right)+3,5:\left(-1,4\right)\)

\(=-1,25\cdot0,75-2,5\)

=-0,9375-2,5

=-3,4375