Question

. Làm tính nhân :

a) \(\left(\sqrt{12}-3\sqrt{75}\right).\sqrt{3}\)

b) \(\left(\sqrt{18}-4\sqrt{72}\right).2\sqrt{2}\)

c) \(\left(\sqrt{6}-2\right)\left(\sqrt{6}+7\right)\)

d) \(\left(\sqrt{3}+2\right)\left(\sqrt{3}-5\right)\)

2 . Thực hiện phép tính :

a) \(\left(\sqrt{48}-\sqrt{27}+4\sqrt{12}\right):\sqrt{3}\)

b) \(\left(\sqrt{20}-3\sqrt{45}+6\sqrt{180}\right):\sqrt{5}\)

c) \(\left(2\sqrt{20}-3\sqrt{45}+4\sqrt{80}\right):\sqrt{5}\)

d) \(\left(3\sqrt{24}+4\sqrt{54}-5\sqrt{96}\right):\sqrt{6}\)

e) \(\left(\sqrt{x^2y}-\sqrt{xy^2}\right):\sqrt{xy}\)

f) \(\left(\sqrt{a^3b}+\sqrt{ab^3}-ab\right):\sqrt{ab}\)

g) \(\left(3\sqrt{x^2y}-4\sqrt{xy^2}+5xy\right):\sqrt{xy}\)

h) \(\left(\sqrt{a^3b}+\sqrt{ab^3}-3\sqrt{ab}\right):\sqrt{ab}\)

Answer 1

1. c)\(\left(\sqrt{6}-2\right)\left(\sqrt{6}+7\right)\)

\(\Leftrightarrow6+7\sqrt{6}-2\sqrt{6}-14\)

\(\Leftrightarrow-8+5\sqrt{6}\)

d)\(\left(\sqrt{3}+2\right)\left(\sqrt{3}-5\right)\)

\(\Leftrightarrow3-5\sqrt{3}+2\sqrt{3}-3\)

\(\Leftrightarrow-3\sqrt{3}\)

Answer 2

@ngonhuminh @ngonhuminh

Answer 3

Bài 2: 

a: \(=\dfrac{4\sqrt{3}-3\sqrt{3}+8\sqrt{3}}{\sqrt{3}}=4-3+8=9\)

b: \(=\dfrac{2\sqrt{5}-9\sqrt{5}+36\sqrt{5}}{\sqrt{5}}=2-9+36=29\)

c: \(=\dfrac{4\sqrt{5}-9\sqrt{5}+16\sqrt{5}}{\sqrt{5}}=4-9+16=11\)

d: \(=\dfrac{6\sqrt{6}+12\sqrt{6}-20\sqrt{6}}{\sqrt{6}}=18-20=-2\)