Đề bài: Khử mẫu của biểu thức dưới dấu căn:
1. \(\sqrt{\frac{4}{5}}\) + \(\sqrt{\frac{1}{2}}\)
2. \(\sqrt{\frac{1}{12}}\) + \(\sqrt{\frac{1}{3}}\)
3. \(\sqrt{\frac{3}{20}}\) - \(\sqrt{\frac{3}{5}}\)
4. ab\(\sqrt{\frac{a}{b}}\)
5. ab\(\sqrt{\frac{1}{ab}}\)
Các bác giúp e vs ạ, hứa sẽ tick, e cảm ơn!!!!!!!
1/\(\sqrt{\frac{4}{5}}\)+\(\sqrt{\frac{1}{2}}\)
=\(\sqrt{\frac{4.5}{5.5}}\)+\(\sqrt{\frac{1.2}{2.2}}\)
= \(5.2.\sqrt{5}\)+\(2\sqrt{2}\)
=\(10\sqrt{5}+2\sqrt{2}\)
2.
\(\sqrt{\frac{1}{12}}\)+\(\sqrt{\frac{1}{3}}\)
=\(\sqrt{\frac{1.12}{12.12}}\)+\(\sqrt{\frac{1.3}{3.3}}\)
=\(12.2\sqrt{3}\)+\(3\sqrt{3}\)
=\(\sqrt{3}\left(24+3\right)\)
=\(27\sqrt{3}\)
3/\(\sqrt{\frac{3}{20}}-\sqrt{\frac{3}{5}}\)
=\(\sqrt{\frac{3.20}{20.20}}\)-\(\sqrt{\frac{3.3}{5.5}}\)
=\(20.2\sqrt{15}\)- 15
=\(40\sqrt{15}-15\)
4/\(ab.\sqrt{\frac{a}{b}}\)
=ab.\(\sqrt{\frac{ab}{b.b}}\)
=\(ab^2\sqrt{ab}\)
\(ab\sqrt{\frac{1}{ab}}=ab\sqrt{\frac{ab}{ab.ab}}\)
=\(2ab\sqrt{ab}\)
