Chuyển các hỗn số thành phân số rồi thực hiện phép tính (theo mẫu) :
a) \(\displaystyle 3{1 \over 2} + 2{1 \over 5} = \;...............\)
b) \(\displaystyle 8{1 \over 3} - 5{1 \over 2} = \;...............\)
c) \(\displaystyle 6{1 \over 7} \times 1{6 \over {43}} =\;..............\)
d) \(\displaystyle 9{1 \over 5}:4{3 \over 5} = \;................\)
a) \(\displaystyle 3{1 \over 2} + 2{1 \over 5} = {7 \over 2} + {{11} \over 5} = {{35} \over {10}} + {{22} \over {10}}\displaystyle = {{57} \over {10}} = 5{7 \over {10}}\)
b) \(\displaystyle 8{1 \over 3} - 5{1 \over 2} = {{25} \over 3} - {{11} \over 2} = {{50} \over 6} - {{33} \over 6} \displaystyle= {{17} \over 6} = 2{5 \over 6}\)
c) \(\displaystyle 6{1 \over 7} \times 1{6 \over {43}} = {{43} \over 7} \times {{49} \over {43}} = {{43 \times 49} \over {7 \times 43}} \displaystyle= {{49} \over 7} = 7\)
d) \(\displaystyle 9{1 \over 5}:4{3 \over 5} = {{46} \over 5}:{{23} \over 5} = {{46} \over 5} \times {5 \over {23}} \) \( \displaystyle= {{46 \times 5} \over {5\times 23}}= {{23 \times 2 \times 5} \over {5\times 23}} =2\)
-- Mod Toán lớp 5
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