Question

Bài 1: Rút gọn biểu thức: a) √50+2√8-3/2√72 + √125 b)(3√2-√5)²-9/√5-√2 c) 5v4a-3v25a + √9a Bài 2: giải phương trình: 7/2√8x-√18x-9-√2x

Answer 1

Bài 1:

a: \(\sqrt{50}+2\sqrt{8}-\dfrac{3}{2}\cdot\sqrt{72}+\sqrt{125}\)

\(=5\sqrt{2}+2\cdot2\sqrt{2}-\dfrac{3}{2}\cdot6\sqrt{2}+\sqrt{125}\)

\(=9\sqrt{2}-9\sqrt{2}+5\sqrt{5}=5\sqrt{5}\)

b: \(\left(3\sqrt{2}-\sqrt{5}\right)^2-\dfrac{9}{\sqrt{5}-\sqrt{2}}\)

\(=18-2\cdot3\sqrt{2}\cdot\sqrt{5}+5-\dfrac{9\left(\sqrt{5}+\sqrt{2}\right)}{5-2}\)

\(=23-6\sqrt{10}-3\left(\sqrt{5}+\sqrt{2}\right)\)

\(=23-6\sqrt{10}-3\sqrt{5}-3\sqrt{2}\)

c: \(5\sqrt{4a}-3\sqrt{25a}+\sqrt{9a}\)

\(=5\cdot2\sqrt{a}-3\cdot5\sqrt{a}+3\sqrt{a}\)

\(=10\sqrt{a}-15\sqrt{a}+3\sqrt{a}=-2\sqrt{a}\)