Luyện tập chung

a.\(\dfrac{18}{15}+\dfrac{7}{15}+\dfrac{12}{15}=\dfrac{18+7+12}{15}=\dfrac{37}{15}\)

b.\(\dfrac{9}{7}+\dfrac{8}{7}+\dfrac{11}{7}=\dfrac{9+8+11}{7}=\dfrac{28}{7}=4\)

61/7

=\(\dfrac{61}{7}\)

=\(\dfrac{61}{7}\)

\(\dfrac{3\times15\times8}{12\times6\times5}=\dfrac{3\times3\times5\times4\times2}{4\times3\times2\times3\times5}=1\)

\(=\dfrac{3\cdot120}{60\cdot6}=\dfrac{2}{2}=1\)

( 4/9 + 7/9 -  2/9 ) x 19/24  = 1 x 19/24 = 19/24

\(=\dfrac{19}{24}\times\left(\dfrac{4}{9}+\dfrac{7}{9}-\dfrac{2}{9}\right)=\dfrac{19}{24}\times1=\dfrac{19}{24}\)

\(\dfrac{19}{24}\times\left(\dfrac{4}{9}+\dfrac{7}{9}-\dfrac{2}{9}\right)\)

\(=\dfrac{19}{24}\times1=\dfrac{19}{24}\)

\(3+\dfrac{9}{4}\times\dfrac{5}{3}=3+\dfrac{3}{4}\times5=3+\dfrac{15}{4}=\dfrac{36}{12}+\dfrac{45}{12}=\dfrac{81}{12}=\dfrac{27}{4}\)

27/4

3 + 15/4 =27/4

1/4=1/2+1/-4

\(\dfrac{1}{4}=\dfrac{1}{6}+\dfrac{1}{12}\)