Question

Tính:

\(\begin{array}{l}a)2.\sqrt 6 .( - \sqrt 6 );\\b)\sqrt {1,44}  - 2.{(\sqrt {0,6} )^2};\\c)0,1.{(\sqrt 7 )^2} + \sqrt {1,69} ;\\d)( - 0,1).{(\sqrt {120} )^2} - \frac{1}{4}.{(\sqrt {20} )^2}\end{array}\)

Answer 1

\(\begin{array}{l}a)2.\sqrt 6 .( - \sqrt 6 )\\ =  - 2.\sqrt 6 .\sqrt 6 \\ =  - 2.{(\sqrt 6 )^2}\\ =  - 2.6\\ =  - 12\\b)\sqrt {1,44}  - 2.{(\sqrt {0,6} )^2}\\ = 1,2 - 2.0,6\\ = 1,2 - 1,2\\ = 0\\c)0,1.{(\sqrt 7 )^2} + \sqrt {1,69} \\ = 0,1.7 + 1,3 \\= 0,7 + 1,3 \\= 2\\d)( - 0,1).{(\sqrt {120} )^2} - \frac{1}{4}.{(\sqrt {20} )^2} \\= ( - 0,1).120 - \frac{1}{4}.20\\ =  - 12 - 5\\ =  - (12 + 5)\\ =  - 17\end{array}\)

Answer 2

a: \(=-2\sqrt{6}\cdot\sqrt{6}=-2\cdot\sqrt{6\cdot6}=-2\cdot6=-12\)

b: \(=1.2-2\cdot0.6=1.2-1.2=0\)

c: \(=0.1\cdot7+1.3=0.7+1.3=2\)

d: \(=-0.1\cdot120-\dfrac{1}{4}\cdot20=-12-5=-17\)