\(\left(3\sqrt{18}+2\sqrt{50}-4\sqrt{72}\right):8\sqrt{2}\) = ?
\(-\dfrac{5}{8}\). \(-\dfrac{3}{4}\). \(\dfrac{5}{8}\). \(\dfrac{1}{4}\). Hướng dẫn giải:\(\left(3\sqrt{18}+2\sqrt{50}-4\sqrt{72}\right):8\sqrt{2}\)\(=\dfrac{3\sqrt{18}}{8\sqrt{2}}+\dfrac{2\sqrt{50}}{8\sqrt{2}}-\dfrac{4\sqrt{72}}{8\sqrt{2}}\)\(=\dfrac{3}{8}.\sqrt{\dfrac{18}{2}}+\dfrac{2}{8}.\sqrt{\dfrac{50}{2}}-\dfrac{4}{8}.\sqrt{\dfrac{72}{2}}\)
\(=\dfrac{3}{8}.\sqrt{9}+\dfrac{2}{8}.\sqrt{25}-\dfrac{4}{8}.\sqrt{36}\)\(=\dfrac{3}{8}.3+\dfrac{2}{8}.5-\dfrac{4}{8}.6\)\(=\dfrac{9+10-24}{8}=-\dfrac{5}{8}\)
