1. I am writting to complain about the dirt and  smoke which comes from  your factory chimneys.

2. Two days ago  I decided  to do my  washing.

3. I washed the sheets and put them out to dry as it was  a nice sunny day and there  was a   breeze.

4. When I take washing in,  I was  horrified  to discover  that it was covered  in  dirty marks.

5. I  assume that the  breeze  I mentioned  carried  the dirt from your chimneys.

6. This is not only  because  of my  sheets but also because  we  have two small children  who are  made to  breath the  same air.

7. Until this incident  I thought your  chimneys  were  safe  and clean.

8. I have  already  written to the  local Member of Parliament about this matter.

9. Furthemore,  I must warn you  that I am going to  write to the  local newspaper tomorrow.

10. I look forward  to  receiving  your  reply.

Vì \(AD\) là tia phân giác của \(BAC\) nên ta có :

\(\dfrac{BD}{DC}=\dfrac{AB}{AC}=\dfrac{6}{8}=\dfrac{3}{4}\)

\(\Rightarrow\dfrac{BD}{3}=\dfrac{DC}{4}\)

Theo dãy tính chất ti số bằng nhau , ta có :

\(\dfrac{BD}{3}=\dfrac{DC}{4}=\dfrac{BC+DC}{3}=\dfrac{10}{7}\)

\(\Rightarrow BD=3.\dfrac{10}{7}=\dfrac{30}{7}\)

\(\Rightarrow DC=4.\dfrac{10}{7}=\dfrac{40}{7}\)

\(\Rightarrow x=\dfrac{30}{7};y=\dfrac{40}{7}\Rightarrow S=4100\)

Xoa mặt bằng tay vài cái , đấm lưng 

Ta có : \(a\left(b-c\right)\left(b+c-a\right)^2+c\left(a-b\right)\left(a+b-c\right)^2-b\left(a-c\right)\left(a+c-b\right)^2=0\left(1\right)\)

Đặt : \(\left[{}\begin{matrix}a+b-c=x\\b+c-a=y\\a+c-b=z\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}a=\dfrac{x+z}{2}\\b=\dfrac{x+y}{2}\\c=\dfrac{y+z}{2}\end{matrix}\right.\)

Khi đó ta có :

\(VT_{\left(1\right)}=\dfrac{x+z}{2}\left(\dfrac{x+y}{2}-\dfrac{y+z}{2}\right).y^2+\dfrac{y+z}{2}\left(\dfrac{x+z}{2}+\dfrac{x+y}{2}\right).x^2-\dfrac{1}{4}\left(x+y\right)\left(x-y\right).z^2\)

\(=\dfrac{x+z}{2}.\dfrac{x-z}{2}.y^2+\dfrac{y+z}{2}.\dfrac{z-y}{2}.x^2+\dfrac{1}{4}\left(x^2-y^2\right)z^2\)

\(=\dfrac{1}{4}\left(x^2-z^2\right).z^2-\dfrac{1}{4}\left(x^2-y^2\right).z^2=0\left(đpcm\right)\)

D

hãy tính khối lượng của

Mh2so4, Nacl

Cho tam giác HQA có HQ = 20 cm ; QA = 29 cm ; AH = 21 cm . Chứng minh tam giác HQA vuông

Cho tam giác DEF, kẻ MN song song với EF (M ∈ DE; N ∈ DF). Biết ME = 10cm; DN = 9cm; DF = 24cm. Tính DM=?

c

Ta phân tích \(24;32\) ra thừa số nguyên tố

\(24=2^2.3.2\)

\(32=2^5\)

\(UCLN\left(24;32\right)=2^3=8\)