Question

1) Tính

a)\(\sqrt{21,8^2-18,2^2}\)

b) \(\sqrt{100.\left(6,5^2-1,6^2\right)}\)

2 Thực hiện phép tính

a) \(A=\left(\sqrt{3}+4\right)^2+\left(\sqrt{3}-1^2\right)\)

b) \(B=\left(\sqrt{5}+\sqrt{2}\right)^2-\left(\sqrt{10}+1\right)^2\)

Answer 1

1,

\(a,=\sqrt{\left(21,8-18,2\right)\left(21,8+18,2\right)}\\ =\sqrt{3,6\cdot40}\\ =\sqrt{36\cdot4}\\ =\sqrt{36}\cdot\sqrt{4}\\ =6\cdot4\\ =24\)

\(b,=10\cdot\sqrt{\left(6,5-1,6\right)\left(6,5+1,6\right)}\\ =10\cdot\sqrt{4,9\cdot8,1}\\ =10\cdot\sqrt{49\cdot0,81}\\ =10\cdot\sqrt{49}\cdot\sqrt{0,81}\\ =10\cdot7\cdot0,9\\ =63\)

2,

\(A=7+4\sqrt{3}+\sqrt{3}-1\\ =6+5\sqrt{3}\\ B=7+2\sqrt{10}-\left(11+2\sqrt{10}\right)\\ =7+2\sqrt{10}-11-2\sqrt{10}\\ =-4\)