Question

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!!!!!!!

Answer 1

1/\(\sqrt{\frac{4}{5}}\)+\(\sqrt{\frac{1}{2}}\)

=\(\sqrt{\frac{4.5}{5.5}}\)+\(\sqrt{\frac{1.2}{2.2}}\)

= \(5.2.\sqrt{5}\)+\(2\sqrt{2}\)

=\(10\sqrt{5}+2\sqrt{2}\)

Answer 2

2.

\(\sqrt{\frac{1}{12}}\)+\(\sqrt{\frac{1}{3}}\)

=\(\sqrt{\frac{1.12}{12.12}}\)+\(\sqrt{\frac{1.3}{3.3}}\)

=\(12.2\sqrt{3}\)+\(3\sqrt{3}\)

=\(\sqrt{3}\left(24+3\right)\)

=\(27\sqrt{3}\)

Answer 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

=\(40\sqrt{15}-15\)

Answer 4

4/\(ab.\sqrt{\frac{a}{b}}\)

=ab.\(\sqrt{\frac{ab}{b.b}}\)

=\(ab^2\sqrt{ab}\)

Answer 5

\(ab\sqrt{\frac{1}{ab}}=ab\sqrt{\frac{ab}{ab.ab}}\)

=\(2ab\sqrt{ab}\)