a

Bài này quá dễ 

x/40 - x/50= 1/3

<=>5x/200 - 4x/200=1/3

<=> x/200= 1/3

<=> x= 200/3.

bạn ê, mik bị ngu toán, lười suy nghĩ ấy mà nên đừng nói dễ hay khó j vs mik

Ờm, k cho mình đi

\(3x\left(x-y\right)+x-y\)

\(=3x\left(x-y\right)+1\left(x-y\right)\)

\(=\left(x-y\right)\left(3x+1\right)\)

\(=\left(x-y\right)\left(3x+1\right)\)

\(\left|2x-3\right|=3-2x\)

\(ĐK:x\le\dfrac{3}{2}\)

\(\Leftrightarrow\left[{}\begin{matrix}2x-3=3-2x\\3-2x=3-2x\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{3}{2}\\0=0\left(đúng\right)\end{matrix}\right.\)

Vậy \(S=\left\{x\in R;x=\dfrac{3}{2}\right\}\)

2 do

3 usually buy

4 press

5 enjoy

6 has

7 goes

8 gets

9 eat

10 doesn't study

11 doesn't eat

12 doesn't water

13 don't go

14 doesn't eat - is

15 Do - go

16 Do - agree

17 Do you have

18 Do you often eat

19 Does - start

20 does he come

21 does - work

22 does

23 does - do

24 does- go

Xét tam giác ABH vuông tại H có:

\(sinB=\dfrac{AH}{AB}=0,5\Rightarrow AB=\dfrac{AH}{0,5}=\dfrac{5}{0,5}=10\)

Xét tam giác ABH vuông tại H có:

\(AB^2=AH^2+BH^2\left(Pytago\right)\)

\(\Rightarrow BH=\sqrt{AB^2-AH^2}=\sqrt{10^2-5^2}=5\sqrt{3}\)

Bài 2: 

Áp dụng định lí Pytago vào ΔEFG vuông tại E, ta được:

\(FG^2=EF^2+EG^2\)

\(\Leftrightarrow FG^2=15^2+5^2=250\)

hay \(FG=5\sqrt{10}\left(cm\right)\)