a: Xét ΔBAC có 

D là trung điểm của AB

M là trung điểm của AC

Do đó: DM là đường trung bình của ΔABC

Suy ra: DM//BC và \(DM=\dfrac{BC}{2}=3.5\left(cm\right)\)

đọc đề mà quạo lun ă:>

dễ mà tự lm ik:333

1,C

2,C

3,C

4,A

1,We have learnt E for 4 years

2,It has been 3 years since I last saw her

3,He has not smoked since last year

4,Loan last wrote to you a month ago

5,Mai began singing when she was 7

6,They stopped produced this...toy long time ago

7, It is 2 hours since we watched TV

8,The last time I heard him was August

9,The last time Mr Brown taught E at this school was on January 10^th

Bài 5: 

a: \(x\left(x-1\right)-x^2+4x=-3\)

\(\Leftrightarrow x^2-x-x^2+4x=-3\)

hay x=-1

i: \(x^2-9x+8=0\)

\(\Leftrightarrow\left(x-1\right)\left(x-8\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=1\\x=8\end{matrix}\right.\)