a)3/4+2/3+5/12 b)7/8-7/16-11/32 c)3/5+2/7+5/6 d)15/16:3/8*3/4

Đáp án:

$a,$ $\dfrac{3}{4}+\dfrac{2}{3}+\dfrac{5}{12}$ $=\dfrac{11}{6}$

$b,$ $\dfrac{7}{8}-\dfrac{7}{16}-\dfrac{11}{32}$ $=\dfrac{3}{32}$

$c,$ $\dfrac{3}{5}+\dfrac{2}{7}+\dfrac{5}{6}$ $=\dfrac{361}{210}$

$d,$ $\:\dfrac{15}{15}:\dfrac{3}{8}\times \dfrac{3}{4}$ $=2$

Giải thích các bước giải:

$a,$ $\dfrac{3}{4}+\dfrac{2}{3}+\dfrac{5}{12}$

$=\dfrac{9}{12}+\dfrac{8}{12}+\dfrac{5}{12}$

$=\dfrac{9+8+5}{12}$

$=\dfrac{22}{12}$ $=\dfrac{11}{6}$

$b,$ $\dfrac{7}{8}-\dfrac{7}{16}-\dfrac{11}{32}$

$=\dfrac{28}{32}-\dfrac{14}{32}-\dfrac{11}{32}$

$=\dfrac{28-14-11}{32}$

$=\dfrac{3}{32}$

$c,$ $\dfrac{3}{5}+\dfrac{2}{7}+\dfrac{5}{6}$

$=\dfrac{126}{210}+\dfrac{60}{210}+\dfrac{175}{210}$

$=\dfrac{126+60+175}{210}$

$=\dfrac{361}{210}$

$d,$ $\:\dfrac{15}{15}:\dfrac{3}{8}\times \dfrac{3}{4}$

$=1\times \dfrac{8}{3}\times \dfrac{3}{4}$

$=1\times \dfrac{8\times \:3}{3\times \:4}$

$=1\times \dfrac{8}{4}$

$=1\times \:2$

$=2$