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Giải Toán lớp 4 Bài: Phân số bằng nhau

Toán lớp 4 trang 112 Bài 1:

a)                                               

$\frac{2}{5}=\frac{2\times 3}{5\times 3}=\frac{\boxed{}}{\boxed{}};\frac{{\displaystyle 4}}{{\displaystyle 7}}=\frac{{\displaystyle 4\times 2}}{{\displaystyle 7\times 2}}=\frac{{\displaystyle \boxed{}}}{{\displaystyle \boxed{}}};\frac{{\displaystyle 3}}{{\displaystyle 8}}=\frac{{\displaystyle 3\times \boxed{}}}{{\displaystyle 8\times 4}}=\frac{{\displaystyle \boxed{}}}{{\displaystyle \boxed{}}};\frac{{\displaystyle 6}}{{\displaystyle 15}}=\frac{{\displaystyle 6:\boxed{}}}{{\displaystyle 15:\boxed{}}}=\frac{{\displaystyle 2}}{{\displaystyle 5}};\frac{{\displaystyle 15}}{{\displaystyle 35}}=\frac{{\displaystyle 15:\boxed{}}}{{\displaystyle 35:\boxed{}}}=\frac{{\displaystyle 3}}{{\displaystyle \boxed{}}};\frac{{\displaystyle 48}}{{\displaystyle 16}}=\frac{{\displaystyle 48:8}}{{\displaystyle 16:\boxed{}}}=\frac{{\displaystyle \boxed{}}}{{\displaystyle \boxed{}}}$                                 

b)    

$\frac{2}{3}=\frac{\boxed{}}{6};\frac{18}{60}=\frac{3}{\boxed{}};\frac{56}{32}=\frac{\boxed{}}{4};\frac{3}{4}=\frac{\boxed{}}{16}.$                                                

Lời giải

a)                                                

$\frac{2}{5}=\frac{2\times 3}{5\times 3}=\frac{\boxed{6}}{\boxed{15}};\frac{{\displaystyle 4}}{{\displaystyle 7}}=\frac{{\displaystyle 4\times 2}}{{\displaystyle 7\times 2}}=\frac{{\displaystyle \boxed{8}}}{{\displaystyle \boxed{14}}};\frac{{\displaystyle 3}}{{\displaystyle 8}}=\frac{{\displaystyle 3\times \boxed{4}}}{{\displaystyle 8\times 4}}=\frac{{\displaystyle \boxed{12}}}{{\displaystyle \boxed{32}}};\frac{{\displaystyle 6}}{{\displaystyle 15}}=\frac{{\displaystyle 6:\boxed{3}}}{{\displaystyle 15:\boxed{3}}}=\frac{{\displaystyle 2}}{{\displaystyle 5}};\frac{{\displaystyle 15}}{{\displaystyle 35}}=\frac{{\displaystyle 15:\boxed{5}}}{{\displaystyle 35:\boxed{5}}}=\frac{{\displaystyle 3}}{{\displaystyle \boxed{7}}};\frac{{\displaystyle 48}}{{\displaystyle 16}}=\frac{{\displaystyle 48:8}}{{\displaystyle 16:\boxed{8}}}=\frac{{\displaystyle \boxed{6}}}{{\displaystyle \boxed{2}}}$                                      

b)                 

$\frac{2}{3}=\frac{\boxed{4}}{6};\frac{18}{60}=\frac{3}{\boxed{10}};\frac{56}{32}=\frac{\boxed{7}}{4};\frac{3}{4}=\frac{\boxed{12}}{16}.$