Question

Bài 2: Thực hiện phép tính:

\(a) \dfrac{-4}{15}+0,25;\)               \(b) 2,5-(\dfrac{-3}{7});\)               \(c) 1\dfrac{1}{4}+3\dfrac{2}{4} ;\)

\(d) \dfrac{-9}{27}-\dfrac{15}{30};\)                 \(e) 1\dfrac{4}{7}:( -1\dfrac{2}{5});\)               \(f) 1\dfrac{3}{8}:( -0,15).\)

Answer 1

a: \(-\dfrac{4}{15}+0,25=-\dfrac{4}{15}+\dfrac{1}{4}=\dfrac{-16}{60}+\dfrac{15}{60}=-\dfrac{1}{60}\)

b: \(2,5-\left(-\dfrac{3}{7}\right)=\dfrac{5}{2}+\dfrac{3}{7}=\dfrac{35}{14}+\dfrac{6}{14}=\dfrac{41}{14}\)

c: \(1\dfrac{1}{4}+3\dfrac{2}{4}=1+3+\dfrac{1}{4}+\dfrac{2}{4}=4+\dfrac{3}{4}=\dfrac{19}{4}\)

d: \(-\dfrac{9}{27}-\dfrac{15}{30}=-\dfrac{1}{3}-\dfrac{1}{2}=\dfrac{-5}{6}\)

e: \(1\dfrac{4}{7}:-1\dfrac{2}{5}=\dfrac{11}{7}:\dfrac{-7}{5}=\dfrac{11}{7}\cdot\dfrac{-5}{7}=\dfrac{-55}{49}\)

f: \(1\dfrac{3}{8}:\left(-0,15\right)=\dfrac{11}{8}:\dfrac{-3}{20}=\dfrac{11}{8}\cdot\dfrac{-20}{3}=\dfrac{-220}{24}=-\dfrac{110}{12}=-\dfrac{55}{6}\)