Question

B=\(\dfrac{3}{\sqrt[3]{2}+1}\)

tính C=3\(\sqrt{2x}-5\sqrt{8x}+7\sqrt{18x}+1\)

Answer 1

\(C=3\sqrt{2x}-5\cdot2\sqrt{2x}+7\cdot3\sqrt{2x}+1\\ =3\sqrt{2x}-10\sqrt{2x}+21\sqrt{2x}+1\\ =14\sqrt{2x}+1\)

Answer 2

\(B=\dfrac{3}{\sqrt[3]{2}+1}\Leftrightarrow B^3=\dfrac{27}{2+1}=\dfrac{27}{3}=9\\ \Leftrightarrow B=\sqrt[3]{9}\)