200,216

23,38

2375,9541

Các bạn tick mình với nha cho tròn điểm hỏi đáp hihi

\(a.\sqrt{20}-\sqrt{45}+3\sqrt{18}-\sqrt{72}\)

= \(2\sqrt{5}-3\sqrt{5}+9\sqrt{2}-6\sqrt{2}=3\sqrt{2}-\sqrt{5}\)

b. \(\left(\sqrt{28}-2\sqrt{3}+\sqrt{7}\right)\sqrt{7}+\sqrt{84}\)

= \(\sqrt{196}-2\sqrt{21}+7+\sqrt{84}\)

= \(14-2\sqrt{21}+7+2\sqrt{21}=21\)

c. \(\left(\sqrt{6}+\sqrt{5}\right)^2-\sqrt{120}\)

= \(6+2\sqrt{30}+5-\sqrt{120}=6+2\sqrt{30}+5-2\sqrt{30}=11\)

d. \(\left(\dfrac{1}{2}-\sqrt{\dfrac{1}{2}}-\dfrac{3}{2}\sqrt{2}+\dfrac{4}{5}\sqrt{200}\right):\dfrac{1}{8}\)

= \(4-\dfrac{8}{\sqrt{2}}-\dfrac{3\sqrt{2}}{4}+\dfrac{32\sqrt{200}}{5}\)

= \(4-\dfrac{8}{\sqrt{2}}-\dfrac{3}{2\sqrt{2}}+\dfrac{32.5.\sqrt{8}}{5}=4-\dfrac{16}{2\sqrt{2}}+32\sqrt{8}\)

= \(\dfrac{8\sqrt{2}-16+256}{2\sqrt{2}}=\dfrac{240+8\sqrt{2}}{2\sqrt{2}}=60\sqrt{2}+4\)

46=(50-10)+(5+1) = XLVI

Tên : Mai An Linh

Lớp : 9

2.

\(\left(\dfrac{5-\sqrt{5}}{\sqrt{5}}-2\right)\left(\dfrac{4}{1+\sqrt{5}}+4\right)\)

\(=\left(\dfrac{5\sqrt{5}-5}{5}-2\right)\left(\dfrac{4\left(1-\sqrt{5}\right)}{1-5}+4\right)\)

\(=\dfrac{5\sqrt{5}-5-10}{5}.\dfrac{4-4\sqrt{5}-16}{-4}\)

\(=\dfrac{5\sqrt{5}-15}{5}.\dfrac{4\sqrt{5}+12}{4}\)

\(=\left(\sqrt{5}-3\right)\left(\sqrt{5}+3\right)\)

\(=5-9=-4\)

1b) \(\sqrt{5\sqrt{3}+5\sqrt{48-10\sqrt{7+4\sqrt{3}}}}\)

\(=\sqrt{5\sqrt{3}+5\sqrt{48-10\sqrt{4+4\sqrt{3}+3}}}\)

\(=\sqrt{5\sqrt{3}+5\sqrt{48-10\sqrt{\left(2+\sqrt{3}\right)^2}}}\)

\(=\sqrt{5\sqrt{3}+5\sqrt{48-20-10\sqrt{3}}}\)

\(=\sqrt{5\sqrt{3}+5\sqrt{28-10\sqrt{3}}}\)

\(=\sqrt{5\sqrt{3}+5\sqrt{25-10\sqrt{3}+3}}\)

\(=\sqrt{5\sqrt{3}+5\sqrt{\left(5-\sqrt{3}\right)^2}}\)

\(=\sqrt{5\sqrt{3}+25-5\sqrt{3}}\)

\(=\sqrt{25}=5\)

1a) \(\sqrt{4+\sqrt{8}}.\sqrt{2+\sqrt{2+\sqrt{2}}}.\sqrt{2-\sqrt{2+\sqrt{2}}}\)

\(=\sqrt{4+\sqrt{8}}.\sqrt{\left(2+\sqrt{2+\sqrt{2}}\right)\left(\sqrt{2-\sqrt{2+\sqrt{2}}}\right)}\)

\(=\sqrt{4+\sqrt{8}}.\sqrt{4-2-\sqrt{2}}\)

\(=\sqrt{4+\sqrt{8}}.\sqrt{2-\sqrt{2}}=\sqrt{\left(4+\sqrt{8}\right)\left(2-\sqrt{2}\right)}\)

\(=\sqrt{8-4\sqrt{2}-\sqrt{16}+2\sqrt{8}}\)

\(=\sqrt{8-4\sqrt{2}-4+4\sqrt{2}}\)

\(=\sqrt{4}=2\)

A = \(\sqrt{\dfrac{\left[\left(x-5\right)^2\right]^2}{\left(4-x\right)^2}}+\dfrac{\left(x-5\right)\left(x+5\right)}{4-x}\)

A = \(\dfrac{\left(x-5\right)^2}{4-x}+\dfrac{\left(x-5\right)\left(x+5\right)}{4-x}\)

A = \(\dfrac{\left(x-5\right)\left(x-5+x+5\right)}{4-x}\)

A = \(\dfrac{2x\left(x-5\right)}{4-x}\)

P/s: Ko biết có sai ko nx :P

Fill in the blank with a, an or the if necessary

1. ..The.. first man to land on .the...moon said: "This is ..a.. small step for..a..man. But a giant step for mankind."

2. Take ...a...seat, I have told you..the..hundred times not to come into ..a.. room with...a..hat on.

I. Chọn một từ/cụm từ thích hợp nhất để hoàn chỉnh các câu sau. Khoanh tròn A, B, C hoặc D ứng với từ/cụm từ đúng như ví dụ (câu 0) đã làm. (1.0p)

0. Nam ______ here three weeks ago.

A. has been B. will be C. was D. is

1. The film was _____ boring that she went home early.

A. too B. so C. such D. very

2. Are these the keys ______ Mrs. Janet has been looking for?

A. who B. what C. whose D. which

3. The pagoda ______ about 1,000 years ago.

A. was built B. is built C. has been built D. will be built

4. If you want to know the meaning of this word, you can look it up _______ the dictionary.

A. at B. in C. for D. to

5. ______ capital of Thailand is Bangkok.

A. A B. An C. The D. X (no article)

6. Would you like a cup of coffee, please? – _____________.

A. No. I don't like. B. Sorry, I don't like. C. No, please. D. Yes, please.

7. Once you get on the trip, you'll be in a _______ world.

A. different B. identical C. corresponding D. distinguished

8. The _______ of natural resources is being talked about by Peter's teacher.

A. preserve B. preservation C. preserver D. preservatory

9. Are there _______ oranges left in the fridge?

A. any B. some C. a little D. lot of

10. If he had got up early yesterday morning, he ______ the bus.

A. missed B. won't miss C. wouldn't miss D. wouldn't have missed

II. Cho dạng đúng của động từ trong ngoặc để hoàn chỉnh câu như ví dụ (câu 0) đã làm. (0.5p)

0. Put the raincoat on. It _________is raining___________ (rain).

1. Peter _________came________________ (come) to Paris to learn French a year ago.

2. The Smiths ______are watching__________ (watch) TV in the sitting room now.

3. She wishes her room _______would be__________ (be) larger.

4. Most children enjoy _______listening________ (listen) to funny story.

5. Thanh's parents don't allow _____to go_______ (go) out at night.