Tính: 3/4+2/3+5/12

Giải Toán lớp 5 Luyện tập chung trang 31

Toán lớp 5 trang 31 Bài 2:

a) $\frac{3}{4}+\frac{2}{3}+\frac{5}{12}$                                             

b) $\frac{7}{8}-\frac{7}{16}-\frac{11}{32}$

c) $\frac{3}{5}\times \frac{2}{7}\times \frac{5}{6}$                                                

d) $\frac{15}{16}:\frac{3}{8}\times \frac{3}{4}$

Lời giải

a) 

$\frac{3}{4}+\frac{2}{3}+\frac{5}{12}=\frac{9}{12}+\frac{8}{12}+\frac{5}{12}=\frac{9+8+5}{12}=\frac{22}{12}=\frac{11}{6}$           

b)

$\frac{7}{8}-\frac{7}{16}-\frac{11}{32}=\frac{28}{32}-\frac{14}{32}-\frac{11}{32}=\frac{28-14-11}{32}=\frac{3}{32}$

c)      

$\frac{3}{5}\times \frac{2}{7}\times \frac{5}{6}=\frac{3\times 2\times 5}{5\times 7\times 6}=\frac{\cancel{3}\times \cancel{2}\times \cancel{5}}{\cancel{5}\times 7\times \cancel{2}\times \cancel{3}}=\frac{1}{7}$                 

d)

$\frac{15}{16}:\frac{3}{8}\times \frac{3}{4}=\frac{15}{16}\times \frac{8}{3}\times \frac{3}{4}=\frac{15\times 8\times 3}{16\times 3\times 4}=\frac{15\times 8\times 3}{8\times 2\times 3\times 4}=\frac{15}{8}$