50 và 55 

có chơi,có chơi

ok!!!!!!!!!!!!

                               Giải

Tích của bán kính và bán kính là:

      200,96:3,14=64(cm)

Vì 8×8=64 nên bán kính của hình tròn là 8cm

Chu vi hình tròn là:

       (2×8)×3,14=50,24(cm)

            ĐS: 50,24cm

Chúc bạn hok tốt!~

Tích bán kính với bán kính hình tròn là :

200,96 : 3,14 = 64(cm)

Vậy bán kính hình trong sẽ là : 8

Chu vi hình tròn là :

8 x 3,14 = 25,12(cm)

Đ/s: 25,12cm

12,5x8+25x5:2-(100:4-12,5)x3

=100+125:2-25-12,5x3

=100+62,5-25-37,5

=100+37,5-37,5                           

=137,5-37,5

100                                                           

tính nhanh ạ

số 99 và 100

Ms. Hien is my English teacher, and she is a really lovely person. Ms. Hien is pretty young – just about 25 years old. She had studied abroad for a long time, and this is the first year that she comes back and teaches in Vietnam. She is tall and slim, and she has beautiful long black hair with bright skin. She is the belle of our school, and I know there are many male teachers that secretly admire her. Since Ms. Hien spent a long time study with foreigners, her English as well as teaching skills are very good. When we first had chance to study with her, we found out that our English was just at the most basic level. She has many new teaching methods, and we can see a real big progress after a while. Most of us are afraid of English, but now we are even looking forward to her class since it is always full of laughter and interesting games that relate to the lesson. Ms. Hien is such a great teacher, and I hope I will have chance to study with her next year.

BẠN THAM KHẢO NHÉ!!!

My favourite teacher is my class teacher. Her name is Nisha Gupta. She takes our attendance and teaches us Hindi, Maths and Art subject. She is well educated and taken higher studies from the Banaras Hindu University. She follows very easy and effective teaching strategies to teach us all the subjects. I never miss her class and attend daily. I the way she teaches us as we do not need to study that subject at home again. We become very clear about the topic she teaches us in the classroom. After clearing the concept of topic, she gives us some exercises in the class and also home work for the home. Next day, she asks questions related to the yesterday topic and then start another topic.

In spite of the subjects, she teaches us good ethics and etiquette also to make us strong by character. May be; she will not be our teacher in next class however; her teachings will always be with us and show us way to difficult situations. She is very caring and loving in nature. She has been the gold medalist in the university she got her higher education. She would always be my best teacher.

12345-3+567-234:3x345:23+5-3

=12345-3+567-78x15+2

=12342+567-1170+2

=12909-1172

=11737

Bài 4:

Số cây nhóm 1 hơn nhóm 2 là:

5 x 2 = 10 (cây)

Sau khi nhóm 2 cho nhóm 1 thì số cây của nhóm 2 là:

10 + 10 x 2 = 30 (cây)

Số cây nhóm 2 ban đầu là:

30 + 10 = 40 (cây)

Số cây nhóm 1 ban đầu là:

40 + 10 = 50 (cây)

ĐS: nhóm 1: 50 cây; nhóm 2: 40 cây

Bài 5

Gọi chiều rộng ban đầu của thửa ruộng là a

Chiều dài ban đầu của thửa ruộng là a x 2

Nếu chiều rộng tăng thêm 20m, chiều dài tăng thêm 15m thì chiều dài gấp rưỡi chiều rộng:

\(\Rightarrow\)(a x 2 + 15) x 2 = (a + 20) x 3

\(\Rightarrow\)4 x a + 30 = 3 x a + 60

\(\Rightarrow\)a = 30 (cùng bớt 2 vế đi a x 3 và 30)

Vậy diện tích thửa ruộng đó là:

a x a x 2 = 30 x 30 x 2 = 1800 (m²)

ĐS: 1800 m²

S một mặt nha

cạnh hình lập phương = 80: 4=20