14 = 11 + 3

Hai tg ABM và tg ABC có chung đường cao từ A->BC nên

\(\dfrac{S_{ABM}}{S_{ABC}}=\dfrac{BM}{BC}=\dfrac{1}{3}\Rightarrow S_{ABM}=\dfrac{1}{3}S_{ABC}\)

Hai tg BCN và tg ABC có chung đường cao từ B->AC nên

\(\dfrac{S_{BCN}}{S_{ABC}}=\dfrac{CN}{AC}=\dfrac{1}{3}\Rightarrow S_{BCN}=\dfrac{1}{3}S_{ABC}\)

\(\Rightarrow S_{ABM}=S_{BCN}=\dfrac{1}{3}S_{ABC}\)

C/m tương tự ta cũng có

\(S_{APC}=S_{BCN}=\dfrac{1}{3}S_{ABC}\)

Ta có

\(S_{KIJ}=S_{ABC}-S_{ABM}-S_{CMIN}-S_{ANJK}=\)

\(=S_{ABC}-S_{ABM}-\left(S_{BCN}-S_{BIM}\right)-\left(S_{APC}-S_{APK}-S_{CJN}\right)=\)

\(=S_{ABC}-\dfrac{1}{3}S_{ABC}-\left(\dfrac{1}{3}S_{ABC}-S_{BIM}\right)-\left(\dfrac{1}{3}S_{ABC}-S_{APK}-S_{CJN}\right)=\)

\(=S_{APK}+S_{BIM}+S_{CJN}\)
 

Today I will introduce everyone to my family. My family has 4 people: my grandfather, my father, my mother and me. My grandfather is 78 years old. He has silver hair and his figure is rather thin. Because of his advanced age, he rarely exercised vigorously. My grandfather has a hobby of growing flowers. Every day he is very careful to take care of his flowers. My father is a doctor. He is very busy. I rarely see my father. My father treats many patients every day. I am very proud of my father. My mom is a teacher. My mother loves me very much. My mother taught me useful things. People often think that my parents are difficult but the truth is the opposite. I am free to do what I . However, thanks to my mother’s guidance, I knew what was right. I often tell my mother my stories and I am happy that she always listens attentively. My mother will give me good advice. Whenever my dad has free time, we cook together. I the feeling of everyone doing something together. Family is where I feel safe and happy. I grew up in a wonderful environment. I hope everything will be as good as it is now.            đây bạn nhé

Gia đình mình có 5 người bố,mẹ,mình và 2 em sinh đôi nhé.Kể về gia đình mình chứ mình không biết sửa lại như thế nào đâu.Thanks

4: Ta có: x+2x+...+18x=1368

\(\Leftrightarrow153x=1368\)

hay \(x=\dfrac{152}{17}\)

Thời gian ô tô chở hàng đi trước ô tô du lịch là :

8 giờ 30 phút - 7 giờ = 1 giờ 30 phút = 1,5 giờ

Quãng đường ô tô chở hàng đi trước ô tô du lịch là :

40 x 1,5 = 60 ( km )

Hiệu vận tốc của hai xe là :

65 - 40 = 25 ( km / giờ )

Thời gian ô tô du lịch đuổi đuổi kịp ô tô chở hàng là :

60 : 25 = 2,4 ( giờ ) = 2 giờ 24 phút 

Ô tô du lịch đuổi kịp ô tô chở hàng lúc :

8 giờ 30 phút + 2 giờ 24 phút = 10 giờ 54 phút

Đáp số : 10 giờ 54 phút

\(\Leftrightarrow3y\left(x+5\right)+2\left(x+5\right)=-25\)

\(\Leftrightarrow\left(3y+2\right)\left(x+5\right)=-25\)

cái này phải thêm x,y thuộc Z nữa chứ k thuộc thì t làm k làm nổi đâu :))