Tính:
a) \(\displaystyle {4 \over 3} + {1 \over 3} + {1 \over 5}\) b) \(\displaystyle {4 \over 3} + {1 \over 3} - {1 \over 5}\)
c) \(\displaystyle {1 \over 2} \times {1 \over 3}:{1 \over 4}\) d) \(\displaystyle {1 \over 2}:{1 \over 3}:{1 \over 4}\)
a) \(\displaystyle {4 \over 3} + {1 \over 3} + {1 \over 5} = {5 \over 3} + {1 \over 5}\displaystyle = {{25} \over {15}} +\dfrac{3}{15}= {{28} \over {15}}\)
b) \(\displaystyle {4 \over 3} + {1 \over 3} - {1 \over 5} = {5 \over 3} - {1 \over 5} \displaystyle = {{25} \over {15}} -\dfrac{3}{15}= {{22} \over {15}}\)
c) \(\displaystyle {1 \over 2} \times {1 \over 3}:{1 \over 4} ={1 \over 6}:{1 \over 4} = {1 \over 6} \times {4 \over 1} \displaystyle = \dfrac{4}{6}= {2 \over 3}\)
d) \(\dfrac{1}{2}:\dfrac{1}{3}:\dfrac{1}{4} = \dfrac{1}{2} \times \dfrac{3}{1}:\dfrac{1}{4} = \dfrac{3}{2}:\dfrac{1}{4} = \dfrac{3}{2} \times \dfrac{4}{1} = \dfrac{{12}}{2} = 6\)
-- Mod Toán lớp 4