works - is having

have been - were invented 

was found 

had been 

was sitting 

am

has given

getting

was

have not finished

Mà h cóa ai bik làm ko giúp mk dới :)) 

\(D=\dfrac{11}{4}\cdot\left(-0,4\right)-\dfrac{8}{5}\cdot2,75+\left(-1,2\right):\dfrac{4}{11}\)

\(D=\dfrac{11}{4}\cdot\left(\dfrac{-2}{5}\right)-\dfrac{8}{5}\cdot\dfrac{11}{4}+\left(\dfrac{-6}{5}\right)\cdot\dfrac{11}{4}\)

\(D=\dfrac{11}{4}\cdot\) \(\left(\dfrac{-2}{5}-\dfrac{8}{5}+\dfrac{-6}{5}\right)\)

\(D=\dfrac{11}{4}\cdot\left(-\dfrac{16}{5}\right)\)

\(D=-\dfrac{44}{5}\)

a) Rút gọn được \(\dfrac{\sqrt{xy}}{x-\sqrt{xy}+y}\)

c) \(H=\dfrac{\sqrt{xy}}{x-\sqrt{xy}+y}\Rightarrow H^2=\dfrac{xy}{\left(x-\sqrt{xy}+y\right)^2}\)

\(\Rightarrow H^2-H=\dfrac{xy}{\left(x-\sqrt{xy}+y\right)^2}-\dfrac{\sqrt{xy}}{x-\sqrt{xy}+y}=\dfrac{xy-\sqrt{xy}\left(x-\sqrt{xy}+y\right)}{\left(x-\sqrt{xy}+y\right)^2}\)

\(=\dfrac{2xy-x\sqrt{xy}-y\sqrt{xy}}{\left(x-\sqrt{xy}+y\right)^2}=\dfrac{-\sqrt{xy}\left(x-2\sqrt{xy}+y\right)}{\left(x-\sqrt{xy}+y\right)^2}=-\dfrac{\sqrt{xy}\left(\sqrt{x}-\sqrt{y}\right)^2}{\left(x-\sqrt{xy}+y\right)^2}\)

Do \(\left\{{}\begin{matrix}\sqrt{xy}\ge0\\\left(\sqrt{x}-\sqrt{y}\right)^2\ge0\\\left(x-\sqrt{xy}+y\right)^2\ge0\end{matrix}\right.\)

\(\Rightarrow H^2-H=-\dfrac{\sqrt{xy}\left(\sqrt{x}-\sqrt{y}\right)^2}{\left(x-\sqrt{xy}+y\right)^2}\le0\Rightarrow H^2\le H\)

Mà \(H\ge0\left(cmt\right)\Rightarrow H\le\sqrt{H}\)

chuẩn đi

Chúc mọi người học tốt

Sức khỏe cũng tốt để thi nha

<3

R nha, hôm kia

Chưa nhưng sắp

=8

tk mk nha

mk se tk lai

= 8

Khỏi cần bn k vì bn có k 100 cái cho Shino thì điểm vẫn vậy ko tăng.

_Shino_

1+1=2

nhanh nao cac bn

luongkun!

2

học tốt

45 k nha

= 45 

aitk mình tk

\(\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+...+\frac{1}{99\cdot100}\)

\(=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{99}-\frac{1}{100}\)

\(=\frac{1}{2}-\frac{1}{100}=\frac{50-1}{100}=\frac{49}{100}\)

1/2*3+1/3*4+.....+1/99*100

=1/2-1/3+1/3-1/4+........1/99*100

=1/2+(-1/3+1/3)+(-1/4+1/4)+.........+(-1/99+1/99)-1/100

=1/2-1/100

=50/100-1/100

=49/100

GT:

`Delta ABC` có `AB = AC`.

`hat(DAB) = hat(DAC) = 1/2 hat(BAC)`

`DA ∩ AI = {I} ( I in BC )`

KL:
`...`

GT: △ABC cân tại A

AI là đường phân giác ( I ∈ BC)

không có câu hỏi hả bạn ?