Question

[Good boy]

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Answer 1

[GV Nguyễn Trần Thành Đạt]

\(2\sqrt{3a}-\sqrt{75a}+a\sqrt{\dfrac{13,5}{2a}}-\dfrac{2}{5}\sqrt{300a^3}=-A.\sqrt{3a}\\ \Leftrightarrow2\sqrt{3a}-\sqrt{5^2.3a}+\sqrt{\dfrac{13,5a^2}{2a}}-\sqrt{\left(\dfrac{2}{5}\right)^2.300a^3}=-A.\sqrt{3a}\\ \Leftrightarrow2\sqrt{3a}-5\sqrt{3a}+\sqrt{6,75a}-\sqrt{48a^3}=-A\sqrt{3a}\\ \Leftrightarrow2\sqrt{3a}-5\sqrt{3a}+\sqrt{\left(1,5\right)^2.3a}-\sqrt{4^2.3a}=-A\sqrt{3a}\\ \Leftrightarrow2\sqrt{3a}-5\sqrt{3a}+1,5\sqrt{3a}-4\sqrt{3a}=-A\sqrt{3a}\\ \Leftrightarrow-5,5\sqrt{3a}=-A\sqrt{3a}\\ Vậy:A=\dfrac{-5,5\sqrt{3a}}{-\sqrt{3a}}=5,5\)

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