Đúng ghi Đ, sai ghi S vào ô trống

Giải Vở bài tập Toán lớp 4 Bài 131: Luyện tập chung

Vở bài tập Toán lớp 4 Tập 2 trang 53 Bài 1:

a) $\frac{5}{9}+\frac{2}{3}=\frac{5+2}{9+3}=\frac{7}{12}\text{\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}□}$                    

b) $\frac{5}{9}+\frac{2}{3}=\frac{5+2}{9\times 3}=\frac{7}{27}\text{\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}□}$ 

c) $\frac{5}{9}+\frac{2}{3}=\frac{5}{9}+\frac{6}{9}=\frac{11}{9}\text{\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}□}$                    

d) $\frac{5}{9}+\frac{2}{3}=\frac{5\times 2}{9+3}=\frac{10}{12}\text{\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}□}$ 

Lời giải:

a) $\frac{5}{9}+\frac{2}{3}=\frac{5+2}{9+3}=\frac{7}{12}\boxed{\text{\hspace{0.17em}S\hspace{0.17em}\hspace{0.17em}}}$                    

b) $\frac{5}{9}+\frac{2}{3}=\frac{5+2}{9\times 3}=\frac{7}{27}\boxed{\text{\hspace{0.17em}\hspace{0.17em}S\hspace{0.17em}\hspace{0.17em}}}$ 

c) $\frac{5}{9}+\frac{2}{3}=\frac{5}{9}+\frac{6}{9}=\frac{11}{9}\boxed{\text{\hspace{0.17em}Đ\hspace{0.17em}\hspace{0.17em}}}$                    

d) $\frac{5}{9}+\frac{2}{3}=\frac{5\times 2}{9+3}=\frac{10}{12}\boxed{\text{\hspace{0.17em}\hspace{0.17em}S\hspace{0.17em}}}$