a)Vì tia Oy và tia Oz cùng nằm trên nữa bờ mặt phẳng chứa tia Ox 

Mà xÔz < xÔm(20⁰ < 100⁰) \(\Rightarrow\)tia Om nằm giữa 2 tia Ox và Ôz

\(\Rightarrow\)xÔz + zÔy = xÔy

thay số: 20⁰  + 100⁰ =zÔy

                       zÔy = 100⁰ - 20⁰

                               zÔy = 80⁰

b) Vì tia Om là tia phân giác của zÔy

\(\Rightarrow\) zÔm và mÔy = \(\frac{zÔy}{2}=\frac{80}{2}\)=40⁰

\(\Rightarrow\) xÔz + zÔm = xÔm

Thay số :20⁰ + 40⁰ =60⁰

**** nha các bạn

b)\(\Leftrightarrow\left(2x-1\right)\left(x-4\right)\left(x-3\right)=0\)

\(\Leftrightarrow\left[\begin{array}{nghiempt}2x-1=0\\x-3=0\\x-4=0\end{array}\right.\)\(\Leftrightarrow\left[\begin{array}{nghiempt}x=\frac{1}{2}\\x=3\\x=4\end{array}\right.\)

\(C=\frac{\sqrt{m}}{\sqrt{\left(x-1\right)^2}}.\frac{4m^3\left(x-1\right)^2}{9}=\frac{\sqrt{m}}{\left(x-1\right)}.\frac{4m^3\left(x-1\right)^2}{9}=\frac{4m^3\sqrt{m}\left(x-1\right)}{9}\)

\(B=\frac{7y\left(y-x\right)\sqrt{7xy}}{2\sqrt{7xy}}=7y^2-7x\)

\(A=\left(\sqrt{6\left(x^2-2xy^2+y^3\right)}+\sqrt{6.4x^2y}\right).\frac{1}{\sqrt{6y}}\)

\(=\left(\sqrt{6\left(x^2-xy^2+y^3\right)}+2x\sqrt{6y}\right).\frac{1}{\sqrt{6y}}\)

\(=\left[\sqrt{6}\left(\sqrt{x^2-xy^2+y^3}+2x\sqrt{y}\right)\right].\frac{1}{\sqrt{6y}}=\sqrt{6}\left(\sqrt{x^2-xy^2+y^3}-2x\sqrt{y}\right).\frac{1}{\sqrt{6}\sqrt{y}}\)

\(=\frac{x^2-xy^2+y^3}{\sqrt{y}}-\frac{2x\sqrt{y}}{\sqrt{y}}=\frac{x^2-xy^2+y^3}{\sqrt{y}}-2x\)

mik chỉ lm đến đây đc thui 

ĐKXĐ \(\Leftrightarrow\sqrt{x}\ge0\Leftrightarrow x\ge0\)

\(2x+3\sqrt{x}-2=0\)

\(\Leftrightarrow2x-\sqrt{x}+4\sqrt{x}-2=0\Leftrightarrow\sqrt{x}\left(2\sqrt{x}-1\right)+2\left(2\sqrt{x}-1\right)=0\)

\(\Leftrightarrow\left(\sqrt{x}+2\right)\left(2\sqrt{x}-1\right)=0\)\(\Leftrightarrow\)\(\left[\begin{array}{nghiempt}\sqrt{x}+2=0\\2\sqrt{x}-1=0\end{array}\right.\)\(\Leftrightarrow\left[\begin{array}{nghiempt}\sqrt{x}=-2\\\sqrt{x}=\frac{1}{2}\end{array}\right.\)\(\Leftrightarrow x=\frac{1}{4}\)

- To wear 

- 

- To live

- To 

- To copy

- To look

- To 

- To borrow 

Sao cho phù hợp với các câu sau: 

a, What time does the next bus leave, please?

b, She can't hears you, I'm afraid. She's deaf

c, I think Peter is going to be an artist. He draws so well.

d, What color is your new shoes?

e, Would you like to come to my party on Friday?

f, Can you look after the children tonight?

g, My brother is living with a French family now.

h, They borrowed many books from the library yesterday afternoon.

I, Shall I wear my blue dress or red dress to the party?

j, Anna always copyes  the way I dress.

Khi 2 vật trao đổi nhiệt với nhau thì : 
_ Nhiệt tự truyền từ vật có nhiệt độ cao hơn sang vật có nhiệt độ thấp hơn. 
_ Sự truyền nhiệt xảy ra cho tới khi nhiệt độ của 2 vật bằng nhau thì dừng lại. 
_ Nhiệt lượng do vật này tỏa ra bằng nhiệt lượng do vật kia thu vào. 

PTHH : Fe₂O₃ + 6HCl ------> 2FeCl₃ + 3H₂O

1. Can Peter repair the bike ? ( skilful )
~> No , he is not skilful 
2. Will you take a rest after lunch ? ( tired )
~> Yes , I will . I am so tired.
3. Can I work qith these men ? ( old )
~> No , you are too old to work with them.
4 . Can she join our club ? ( old )
~> Yes, she is old enough to join our club
5. Can thay hang the picture on the wall ? ( tall )
~> No, they is not tall enough 
6. Did you wear this coat last winter ? ( cold )
~> No , it was not very cold
7. Can you listen to the music on the radio ? ( clear )
~> No, it is not clearly
8. Will you buy the new CD of the band ? ( good )
~> Yes, the songs are very good
9. Can we swim early in the morning these days ? ( warm ) 
~> Yes, the water is warm 
10. Why don't we sit outside? ( cool )
~> Yes, it's very cool