\(a,\dfrac{6}{7}+\dfrac{5}{7}=\dfrac{12}{7}\)
\(b,\dfrac{4}{9}-\dfrac{1}{6}=\dfrac{24}{54}-\dfrac{9}{54}=\dfrac{15}{54}=\dfrac{5}{18}\)
\(c,\dfrac{3}{10}\times\dfrac{4}{9}=\dfrac{12}{90}=\dfrac{2}{15}\)
\(d,3:\dfrac{1}{2}=3\times2=6\)
Lời giải:
a.
$\frac{6}{7}+\frac{5}{7}=\frac{11}{7}$
b.
$\frac{4}{9}-\frac{1}{6}=\frac{8}{18}-\frac{3}{18}=\frac{5}{18}$
c.
$\frac{3}{10}\times \frac{4}{9}=\rac{12}{90}=\frac{12:6}{90:6}=\frac{2}{15}$
d.
$3: \frac{1}{2}=3\times 2=6$
\(a,\dfrac{6}{7}+\dfrac{5}{7}=\dfrac{6+5}{7}=\dfrac{11}{7}\)
\(b,\dfrac{4}{9}-\dfrac{1}{6}=\dfrac{8}{18}-\dfrac{3}{18}=\dfrac{8-3}{18}=\dfrac{5}{18}\)
\(c,\dfrac{3}{10}\times\dfrac{4}{9}=\dfrac{3\times4}{10\times9}=\dfrac{12}{90}=\dfrac{2}{15}\)
\(d,3:\dfrac{1}{2}=3\times\dfrac{2}{1}=\dfrac{6}{1}=6\)
b,49−16=2454−954=1554=518b,49−16=2454−954=1554=518
d,3:12=3×2=6
