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17 tháng 10 2021

undefinedbài này nha mn. ko cần làm bài trên đâu ạ 

17 tháng 10 2021

Mình làm bài ở phần dưới nha!

1. A

2. C

3. D

4. C

5. B

6. D

25 tháng 7 2020

em cháo anh

em giải được đấy 

dạ 534537678657gbjgffgbnsy n58ynvu g3yvt7845y75y4 ko làm mà đòi có ăn

25 tháng 7 2020

em em đánh xin lỗi

5 tháng 11 2021

2 she had got the price of the contest, she would be happy now

3 I had gone to the concert last night ,I would be tired

4 John had finished all his homework, he could see a movie now

5 we had listened to my mother, we wouldn't be in trouble right now

Ex5

1 you arrive at the offcie earlier than I do, please turn on the air-conditioner

2 Were it not snowy, the children would go to school

3 he not died so young, he would be a famous musician

4 Were I you, I would take care of my car

5 not very bad-tempered, his wife would give him soon are marrage

6 Had she not got married at such an early age, he would be at university

Chọn A

13 tháng 10 2020

cau 1 phan h thanh nhan tu roi chia truong hop giai 

cau 2 an may tinh cho nhanh

cau 3 4 bo ngoac roi tim x nhu binh thuong la xong

Câu 2: 

Ta có: \(x^2-2\left(m+1\right)x+m^2+4=0\)

a=1; b=-2m-2; \(c=m^2+4\)

\(\text{Δ}=b^2-4ac\)

\(=\left(-2m-2\right)^2-4\cdot\left(m^2+4\right)\)

\(=4m^2+8m+4-4m^2-16\)

=8m-12

Để phương trình có hai nghiệm phân biệt thì Δ>0

\(\Leftrightarrow8m>12\)

hay \(m>\dfrac{3}{2}\)

Áp dụng hệ thức Vi-et, ta được:

\(\left\{{}\begin{matrix}x_1+x_2=2\left(m+1\right)=2m+2\\x_1x_2=m^2+4\end{matrix}\right.\)

Vì x1 là nghiệm của phương trình nên ta có: 

\(x_1^2-2\left(m+1\right)\cdot x_1+m^2+4=0\)

\(\Leftrightarrow x_1^2=2\left(m+1\right)x_1-m^2-4\)

Ta có: \(x_1^2+2\left(m+1\right)x_2=2m^2+20\)

\(\Leftrightarrow2\left(m+1\right)x_1-m^2-4+2\left(m+1\right)x_2-2m^2-20=0\)

\(\Leftrightarrow2\left(m+1\right)\left(x_1+x_2\right)-3m^2-24=0\)

\(\Leftrightarrow2\left(m+1\right)\cdot\left(2m+2\right)-3m^2-24=0\)

\(\Leftrightarrow4m^2+8m+4-3m^2-24=0\)

\(\Leftrightarrow m^2+8m-20=0\)

Đến đây bạn tự tìm m là xong rồi

23 tháng 7 2021

Cảm ơn b nha

5 tháng 5 2021

Vietnam is famous with its traditional and delicious dishes. All of them easioly bring to anyone's mouth indeed, but as myself, I enjoy spring rolls best. Spring rolls are lightly fried rice -paper rolls, smaller and crispier than Chinese egg rolls but more flavorful. They are filled with highly seasons morsels of crab, shrimp, chopped vegetables, onion, mushroom, vermicelli and eggs. To prepare them, place the above mentioned filling on a thin rice pancake, roll up then fry. Finally, spring rolls, when fully prepared, are wrapped into some kinds of fresh vegetables, then doused in fish sauce. My mother usually cooks spring rolls for me, especially on important days in year, such as Tet holiday. When I eat them, I feel all of my mother's love that she reserves for me. To me, they're like the most special dish in this world

7:

A+B

\(=x^4-2xy+y^2+y^2+2xy+x^2+1\)

=x^4+2y^2+x^2+1

A-B

=x^4-2xy+y^2-y^2-2xy-x^2-1

=x^4-4xy-x^2-1

5:

a: =8x^2-4x^2=4x^2

b: =(5-7)*x^2y^3z^3=-2x^2y^3z^3

c: =(3+2-1/3-1/2-1/6)*x^2y^2

=4x^2y^2