Tính (theo mẫu):

a) $\frac{4}{5}+\frac{1}{2}=\mathrm{................................................}$

b) $\frac{3}{5}+\frac{2}{7}=\mathrm{..................................................}$

c) $\frac{4}{9}-\frac{1}{7}=\mathrm{...................................................}$

d) $\frac{7}{8}-\frac{2}{9}=\mathrm{................................................}$

Bài giải

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Nói cho bạn nghe cách thực hiện cộng, trừ hai phân số cùng mẫu số. Viết ví dụ minh hoạ.

Ví dụ: ......................................................................................................................

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Viết tiếp vào chỗ chấm cho thích hợp:

Tính:

a) $\frac{4}{3}+\frac{5}{6}=\mathrm{.............................................................}$

b) $\frac{2}{5}-\frac{3}{10}=\mathrm{..........................................................}$

c) $6+\frac{7}{2}=\mathrm{...........................................................}$

d) $\frac{9}{2}-1=\mathrm{............................................................}$