Bài 1 :
1. \(\sqrt{50}.\sqrt{2}-\sqrt{0,4}.\sqrt{0,81}.\sqrt{1000}\\=\sqrt{50.2}-\sqrt{0,4.10.0,81.100}\\ =\sqrt{100}-\sqrt{4}.\sqrt{0,81}.\sqrt{100}\\ =10-2.0,9.10\\ =10-18\\ =-8 \)
2. \(\sqrt{81.49}+\sqrt{\left(1-\sqrt{2}\right)^2}-\sqrt{\left(1+\sqrt{2}\right)^2}\\ =\sqrt{81}.\sqrt{49}+\left|1-\sqrt{2}\right|-\left|1+\sqrt{2}\right|\\ =9.7+\sqrt{2}-1-1-\sqrt{2}\\ =61\)
3. \(-2\sqrt{3}+\left(\sqrt{3}+\sqrt{2}\right)^2+\left(\sqrt{3}-\sqrt{2}\right)^2\\ =-2\sqrt{3}+\left(3+2\sqrt{6}+2\right)+\left(3-2\sqrt{6}+2\right)\\ =-2\sqrt{3}+10\)
1) \(\sqrt{50}.\sqrt{2}-\sqrt{0,4}.\sqrt{0,81}.\sqrt{1000}\)
\(=\sqrt{100}-\sqrt{4}.\sqrt{81}\\ =10-2.9\\ =10-18\\ =-8\)
2) \(\sqrt{81.49}+\sqrt{\left(1-\sqrt{2}\right)^2}-\sqrt{\left(1+\sqrt{2}\right)^2}\)
\(=\sqrt{81}.\sqrt{49}+\left|1-\sqrt{2}\right|-\left|1+\sqrt{2}\right|\\ =9.7+\sqrt{2}-1-1-\sqrt{2}\\ =63-2\\ =61\)
3) \(-2\sqrt{3}+\left(\sqrt{3}+\sqrt{2}\right)^2+\left(\sqrt{3}-\sqrt{2}\right)^2\)
\(=-2\sqrt{3}+5+2\sqrt{6}+5-2\sqrt{6}\\ =10-2\sqrt{3}\)
