\(5,\sqrt{\dfrac{1}{4}}+\sqrt{\dfrac{1}{9}}+\sqrt{\dfrac{1}{36}}+\sqrt{\dfrac{1}{16}}\)
\(=\sqrt{\left(\dfrac{1}{2}\right)^2}+\sqrt{\left(\dfrac{1}{3}\right)^2}+\sqrt{\left(\dfrac{1}{6}\right)^2}+\sqrt{\left(\dfrac{1}{4}\right)^2}\)
\(=\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{6}+\dfrac{1}{4}\)
\(=\left(\dfrac{1}{3}+\dfrac{1}{6}\right)+\left(\dfrac{1}{2}+\dfrac{1}{4}\right)\)
\(=\left(\dfrac{2}{6}+\dfrac{1}{6}\right)+\left(\dfrac{2}{4}+\dfrac{1}{4}\right)\)
\(=\dfrac{3}{6}+\dfrac{3}{4}\)
\(=\dfrac{1}{2}+\dfrac{3}{4}\)
\(=\dfrac{2}{4}+\dfrac{3}{4}\)
\(=\dfrac{5}{4}\)
Sửa đề: \(7,\sqrt{0,04}+\sqrt{0,09}+\sqrt{\dfrac{9}{25}}\)
\(=\sqrt{\dfrac{1}{25}}+\sqrt{\dfrac{9}{100}}+\sqrt{\left(\dfrac{3}{5}\right)^2}\)
\(=\sqrt{\left(\dfrac{1}{5}\right)^2}+\sqrt{\left(\dfrac{3}{10}\right)^2}+\dfrac{3}{5}\)
\(=\dfrac{1}{5}+\dfrac{3}{10}+\dfrac{3}{5}\)
\(=\left(\dfrac{1}{5}+\dfrac{3}{5}\right)+\dfrac{3}{10}\)
\(=\dfrac{4}{5}+\dfrac{3}{10}\)
\(=\dfrac{8}{10}+\dfrac{3}{10}\)
\(=\dfrac{11}{10}\)