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 \(DM=\dfrac{BC}{2}=3.5\left(cm\right)\)

Bài 1

Hình 1 Tam giác ABC = ADE

Bài 2

Hình 2 Tam giác MRQ = NRS = QPT = OST

1.I think you ought to give up playing video games. (should)

-->I think you should give up playing video games.

2.It's necessary for me to finish the work on time. (have to)

--->I have to finish the work on time.

3.It wasn't necessary for you to clean that car. (have to)

--->You didn't have to clean that car.

4.It was quite unnecessary for you to adopt a green lifestyle. (have to)

---->You didn't have to adopt a green lifestyle.

5.It was careless of you to leave the windows open last night. (shouldn't)

----->You shouldn't have left the windows open last night.

6.It is advisable for each member in the family to share the housework equally. (should)

---->Each member in the family should share the housework equally.

7.You are required to come back home before 10 p.m. (must)

--->You must come back home before 10 p.m.

8.Lina is advised to prepare carefully in the morning. (should)

----->Lina should prepare carefully in the morning.

9.Tu is responsible for picking up litter. (have to)

------>Tu has to pick up litter.

1.You are required to ask your parents for permission before staying out late. (must)

You must ask your parents for permission before staying out late.

2.I think you ought to give up smoking immediately. (should)

I think you should give up smoking immediately.

3.It is not a good idea for me to stay up late. (shouldn't)

I shouldn't stay up late.

4.It wasn't necessary for you to send these letters. (have to)

You didn't have to send these letters.

5.It was unnecessary for Tim to finish the work. (have to)

Tim didn't have to finish the work.

6.It was careless of you to leave your children alone at home. (shouldn't)

You shouldn't have left your children alone at home.

Bằng 1 cách nào đó 1 câu hỏi từ 2023 ở đây và tôi vẫn trả lời nó sau 1 năm :v

Mình nghĩ là bài 4, câu a là 6 học sinh chỉ giỏi môn Tiếng Anh.

Còn câu b thì là lớp 9A có 62.

Mình nghĩ vậy thôi chứ chưa chắc đúng. Bài toán khó quá, mình cũng ko bit mình nói đúng hay sai nữa.

mn giúp mink 

mn giúp mink nha

=>(-4) x y -5= -9

=>(-4) x y= -4

=> y=1

giúp j vậy

?

?

3.10:

Hồng đến lúc:

10h40p+15p=10h55p

Hương phải đợi Hồng trong:

10h55p-10h20p=35p

3.9:

a: (3 giờ 25 phút-1 giờ 40 phút)*5

=(2 giờ 85 phút-1 giờ 40 phút)*5

=(1 giờ 45 phút)*5

=5 giờ 225 phút

=8 giờ 45 phút

b: (25 phút 30 giây+1 giờ 58 phút 50 giây):2

=(24 phút 90 giây+118 phút 50 giây):2

=142 phút 140 giây:2

=71 phút 70 giây

=72 phút 10 giây

c: 3 giờ 25 phút+1 giờ 40 phút*5

=3 giờ 25 phút+5 giờ 200 phút

=8 giờ 225 phút

=11 giờ 45 phút

d: 25p30s+1h58p50s:2

=25p30s+118p50s:2

=25p30s+59p25s

=84p55s

e: 2 giờ 15 phút*3+3 giờ 45 phút*2

=6 giờ 45 phút+6 giờ 90 phút

=12 giờ 135 phút

=14 giờ 15 phút

\(21_{10}=10101_2\)