Tính
a) \(\displaystyle {4 \over {10}} + {7 \over {10}} = \,... ;\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\quad{{18} \over 5} - {4 \over 5} = \,...\)
b)
\(\eqalign{ & {5 \over 7} + {4 \over 9} = \,... \quad \quad \quad \quad{4 \over 5} - {2 \over 3} = \,... \cr & {9 \over {11}} + {3 \over 8} = \,... \quad \quad \quad \; {{16} \over {25}} - {2 \over 5} = \,... \cr} \)
a)
\(\eqalign{ & {4 \over {10}} + {7 \over {10}} = {{4 + 7} \over {10}} = {{11} \over {10}}\cr & {{18} \over 5} - {4 \over 5} = {{18 - 4} \over 5} = {{14} \over 5} \cr}\)
b) \(\dfrac{5}{7}+\dfrac{4}{9}=\dfrac{45}{63}+\dfrac{28}{63}=\dfrac{73}{63}\)
\(\dfrac{4}{5}-\dfrac{2}{3}=\dfrac{12}{15}-\dfrac{10}{15}=\dfrac{2}{15}\)
\(\dfrac{9}{11}+\dfrac{3}{8}=\dfrac{72}{88}+\dfrac{33}{88}=\dfrac{105}{88}\)
\(\dfrac{16}{25}-\dfrac{2}{5} =\dfrac{16}{25}-\dfrac{10}{25}=\dfrac{6}{25}\)
-- Mod Toán lớp 5
Copyright © 2021 HOCTAP247