Tính hợp lí: $\frac{2}{7}$+$\frac{1}{9}$+$\frac{3}{7}$+$\frac{5}{9}$+$\frac{7}{10}$

$\dfrac{2}{7}+$$\dfrac{1}{9}+$$\dfrac{3}{7}+$$\dfrac{5}{9}+$$\dfrac{7}{10}$

$=(\dfrac{2}{7}+$$\dfrac{3}{7})+($$\dfrac{1}{9}+$$\dfrac{5}{9})+$$\dfrac{7}{10}$

$=\dfrac{5}{7}+$$\dfrac{2}{3}+$$\dfrac{7}{10}$

$=\dfrac{150}{210}+$$\dfrac{140}{210}+$$\dfrac{147}{210}$

$=\dfrac{437}{210}$

$\text{KL:Vậy: }$$\dfrac{2}{7}+$$\dfrac{1}{9}+$$\dfrac{3}{7}+$$\dfrac{5}{9}+$$\dfrac{7}{10}=$$\dfrac{437}{210}$

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$\text{#mct}$