Bài 1 tính

1/2 - 1/6 - 1/9=

5/6 x 3/4 x 4/2=

4/15 : 7/30=

Đáp án+Giải thích các bước giải:

$\dfrac{1}{2}$ - $\dfrac{1}{6}$ 

= $\dfrac{3}{6}$ - $\dfrac{1}{6}$

= $\dfrac{3-1}{6}$

= $\dfrac{2}{6}$

= $\dfrac{1}{3}$

$\dfrac{5}{6}$ x $\dfrac{3}{4}$ x $\dfrac{4}{2}$

= $\dfrac{5}{6}$ x $\dfrac{3}{4}$ x $\dfrac{2}{1}$

= $\dfrac{5\times3\times2}{6\times4\times1}$

= $\dfrac{30}{24}$

= $\dfrac{5}{4}$

$\dfrac{4}{15}$ : $\dfrac{7}{30}$

= $\dfrac{4}{15}$ x $\dfrac{30}{7}$

= $\dfrac{4$\times$30}{15$\times7}$

= $\dfrac{120}{105}$

= $\dfrac{8}{7}$