\(a,VP=\left(x+2y\right)\left(x^2-2xy+4y^2\right)\\ =\left(x+2y\right)\left[x^2-x.2y+\left(2y\right)^2\right]\\ =x^3+\left(2y\right)^3=x^3+8y^3=VT\left(đpcm\right)\\ b,VT=\left(x-y\right)\left(x^2+xy+y^2\right)-3xy\left(x-y\right)\\ =x^3-y^3-3xy\left(x-y\right)\\ =x^3-3x^2y+3xy^2-y^3\\ =\left(x-y\right)^3=VP\left(đpcm\right)\)

\(c,VT=\left(x-3y\right)\left(x^2+3xy+9y^2\right)-\left(3y+x\right)\left(9y^2-3xy+x^2\right)\\ =\left(x-3y\right)\left[x^2+x.3y+\left(3y\right)^2\right]-\left(x+3y\right).\left[x^2-x.3y+\left(3y\right)^2\right]\\ =x^3-27y^3-\left(x^3+27y^3\right)\\ =-54y^3=VP\left(đpcm\right)\)

b, \(x^5+x+1=x^5-x^2+x^2+x+1\\ =x^2\left(x^3-1\right)+\left(x^2+x+1\right)\\ =x^2\left(x-1\right)\left(x^2+x+1\right)+\left(x^2+x+1\right)\\ =\left(x^2+x+1\right)\left[x^2\left(x+1\right)+1\right]\\ =\left(x^2+x+1\right)\left(x^3-x^2+1\right)\)

`@` `\text {Ans}`

`\downarrow`

\(-\dfrac{3}{2}\cdot\left(\dfrac{4}{5}-\dfrac{2}{3}\right)+x=4\left(x-\dfrac{1}{2}\right)\)

\(\Leftrightarrow-\dfrac{3}{2}\cdot\dfrac{2}{15}+x=4x-2\)

\(\Leftrightarrow-\dfrac{1}{5}+x=4x-2\)

\(\Leftrightarrow-\dfrac{1}{5}+2=-x+4x\)

\(\Leftrightarrow\dfrac{9}{5}=3x\)

\(\Leftrightarrow x=\dfrac{9}{5}\div3\)

\(\Leftrightarrow x=\dfrac{3}{5}\)

Vậy, `x=`\(\dfrac{3}{5}\)

-3/2(4/5-2/3)+x=4(x-1/2)

=>-6/5+1+x=4x-2

=>-1/5-2=4x-x

=>-11/5=3x

=>x=-11/5:3=-11/15.

`@` `\text {Ans}`

`\downarrow`

`3.`

\(\left(\dfrac{1}{2}-x\right)+\dfrac{1}{3}=\dfrac{7}{6}-x\)

\(\Leftrightarrow\dfrac{1}{2}-x+\dfrac{1}{3}=\dfrac{7}{6}-x\)

\(\Leftrightarrow\dfrac{1}{2}+\dfrac{1}{3}-\dfrac{7}{6}=-x+x\)

\(\Leftrightarrow-\dfrac{1}{3}=0\left(\text{Vô lý}\right)\)

Vậy, `x` không có giá trị nào thỏa mãn.

giúp mik với

\(\dfrac{1}{3}\)

giúp mik với ạ

\(x+\left(\dfrac{1}{2}-x\right).\dfrac{1}{3}=\dfrac{7}{6}-x\)

\(\Leftrightarrow x+\dfrac{1}{6}-\dfrac{1}{3}x=\dfrac{7}{6}-x\)

\(\Leftrightarrow2x-\dfrac{1}{3}x=1\)

\(\Leftrightarrow6x-x=3\Leftrightarrow5x=3\Rightarrow x=\dfrac{3}{5}\)

x+(\(\dfrac{1}{2}\)-x)\(\dfrac{1}{3}\)=\(\dfrac{7}{6}\)-x

=>\(\dfrac{1}{6}\)-\(\dfrac{1}{3}\)x=\(\dfrac{7}{6}\)-x-x=\(\dfrac{7}{6}\)-2x

=>\(\dfrac{1}{6}\)-\(\dfrac{7}{6}\)=-2x+\(\dfrac{1}{3}\)x

=>-1=\(\dfrac{-5}{3}\)x

=>1=\(\dfrac{5}{3}\)x

=>x=1:\(\dfrac{5}{3}\)=\(\dfrac{3}{5}\).

Câu a em check lại đề xem mũ 3 hay mũ 4 nhé

mũ 4 chị ơi

1. Her new house is smaller than her old one.
2. Peter is the tallest person in my class.
3. The white dress is less expensive than the black one.
4. According to me, Maths is more difficult than English.
5. Mary is the most intelligent person in my group.
6. The Nile is the longest river in the world.
7. No mountain is higher than Mount Everest.
8. She is the prettiest girl I have ever met.
9. The more he works, the more tired he feels.
10. That computer works worse than this one.

1. The movie was more interesting than the one on TV.
2. We've got less time than I thought.
3. This shirt is too small. I need a larger one.
4. Lan is cleverer and prettier than Lien.
5. She is nicer than I expected.
6. This was the biggest farm I've ever visited.
7. Who between the two workers is the better one?
8. This old machine is more powerful than we thought.
9. The farmers have never had a richer harvest than that.
10. Which is more difficult, English or Math?

1. Mary is older than Julie.
2. The Alps are higher than any other mountains in Europe.
3. An ocean is larger than a sea.
4. A Rolls Royce is more expensive than a Twingo.
5. Fred's results were worse than John's.
6. This exercise is easier than I expected.
7. I hope the weather will be better next week.
8. People are usually friendlier in small towns than in big cities.
9. In the government of a country, the President is the most important person.
10. People say that Chinese is more difficult to learn than English.

(compare more).