Question

Câu 3.Thực hiện phép tính:

a)\(\sqrt{25}-3\sqrt{\dfrac{4}{9}}\)

b)\(\left(2-\dfrac{5}{3}\right):\left(\dfrac{2}{7}+\dfrac{5}{21}-1\right)\)

Answer 1

a) \(\sqrt{25}-3\sqrt{\dfrac{4}{9}}\)
\(=5-2\)
\(=3\)
b) \(\left(2-\dfrac{5}{3}\right):\left(\dfrac{2}{7}+\dfrac{5}{21}-1\right)\)
\(=\left(\dfrac{6}{3}-\dfrac{5}{3}\right):\left(\dfrac{6}{21}+\dfrac{5}{21}-\dfrac{21}{21}\right)\)
\(=\dfrac{1}{3}:\left(-\dfrac{10}{21}\right)\)
\(=\dfrac{1}{3}.\left(-\dfrac{21}{10}\right)\)
\(=-\dfrac{7}{10}\)