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13 tháng 7 2023

Ta có

\(\left(x+x\right)^3=x^3+3x^2y+3xy^2+y^3=x^3+y^3+3xy\left(x+y\right)\)

\(\Rightarrow x^3+y^3=\left(x+y\right)^3-3xy\left(x+y\right)\)

\(\Rightarrow K=\left(x+y\right)^3-3xy\left(x+y\right)+3xy\) Với x+y=1

\(\Rightarrow K=1^3-3xy+3xy=1\)

 

\(\text{∘ Ans}\)

\(\downarrow\)

\(\left(x^2-5x+4\right)\left(2x+4\right)-\left(2x^2-x-10\right)\left(x-3\right)\)

`= 2x(x^2 - 5x + 4) + 4(x^2 - 5x + 4) - [x(2x^2 - x - 10) - 3(2x^2 - x - 10) ]`

`= 2x^3 - 10x^2 + 8x + 4x^2 - 20x + 16 - (2x^3 - x^2 - 10x - 6x^2 + 3x + 30)`

`= 2x^3 - 6x^2 - 12x + 16 - 2x^3 + x^2 + 10x + 6x^2 - 3x - 30`

`= (2x^3 - 2x^3) + (-6x^2 + 6x^2 + x^2) + (-12x + 10x - 3x) + (16 - 30)`

`= x^2 - 5x - 14`

Bạn xem lại đề.

One of the biggest trends in television in recent years has been the rise of “Reality TV”. These shows, in which ordinary people are placed in unusual situations and then filmed without a script, have become some of the highest rating shows on television. Early programs of this genre, including Big Brother (from the Netherlands) and Survivor (from the United States), have led to dozens of copycat programs in many different countries. A common element to many of these programs is that a...
Đọc tiếp

One of the biggest trends in television in recent years has been the rise of “Reality TV”. These shows, in which ordinary people are placed in unusual situations and then filmed without a script, have become some of the highest rating shows on television. Early programs of this genre, including Big Brother (from the Netherlands) and Survivor (from the United States), have led to dozens of copycat programs in many different countries. A common element to many of these programs is that a number of contestants are placed in a closed environment in which they are filmed 24 hours a day, and every week contestants are thrown off the show. What is it about these shows that makes them so popular? Perhaps it is because viewers enjoy watching ordinary people with real emotions being placed in extraordinary, situations. Or perhaps it is that people are really voyeurs - they enjoy being a spy, looking secretly into other people’s lives.

1. In recent years, "Reality TV has become more and more_______.

A. interesting                          B. unusual                          C. popular(dòng 1)          D. enjoyable

2. The underlined word ‘‘which” in the passage refers to_______.

A. a common element            B. a closed environment                          C. every week   D. the show

3. We can see that Big Brother is_______.

A. from the Netherlands                                                   B. from the United States

C. a copycat program                                                        D. shown in many different countries

1
15 tháng 7 2023

3. A

12 tháng 7 2023

giúp với

 

12 tháng 7 2023

\(\left(x-y\right)^2+2xy⋮4\)

\(\Rightarrow x^2-2xy+y^2+2xy⋮4\)

\(\Rightarrow x^2+y^2⋮4\)

\(\Rightarrow x^2⋮4;y^2⋮4\)

mà \(4⋮2\)

\(\Rightarrow x^2⋮2;y^2⋮2\Rightarrow x⋮2;y⋮2\)

\(\Rightarrow dpcm\)

12 tháng 7 2023

 Bài làm của bạn Trí từ chỗ \(x^2+y^2⋮4\Rightarrow x^2,y^2⋮4\) thì bạn còn phải xét thêm trường hợp \(x,y\) cùng lẻ nữa. Vì số chính phương khi chia cho 4 chỉ có thể dư 0 hoặc 1 nên nếu \(x,y\) lẻ thì \(x^2+y^2\) chia 4 dư 2, không thỏa mãn. Vậy mới suy ra được \(x^2,y^2⋮4\). Còn lại bạn đúng hết rồi.

12 tháng 7 2023

a) \(x^2+2xy^3-3z+4xy-5xy^2+2xy-5z\)

\(=x^2+2xy^3-5xy^2-\left(3z+5z\right)+\left(4xy+2xy\right)\)

\(=x^2+2xy^3-5xy^2-8z+6xy\)

b) \(\left(x-3y\right)\left(x^2-3xy+9y^2\right)\)

\(=\left(x-3y\right)\left[x^2-x\cdot3y+\left(3y\right)^2\right]\)

\(=x^3-\left(3y\right)^3\)

\(=x^3-27y^3\)

c) \(\left(2x-y\right)\left(2x+y\right)\)

\(=\left(2x\right)^2-y^2\)

\(=4x^2-y^2\)

d) \(\left(3x-y\right)\left(2y+5\right)-16x4y\)

\(=6xy+15x-2y^2-5y-64xy\)

\(=-58xy+15x-2y^2-5y\)

12 tháng 7 2023

Bạn xem lại đề bài nhé!

11 tháng 7 2023

(\(x\) - 2)2 ≥ 0 \(\forall\) \(x\) 

-(\(x\) - 2)2 ≤ 0 \(\forall\) \(x\)

11 tháng 7 2023

Không có x nào thỏa điều kiện \(-\left(x-2\right)^2\ge0\)

11 tháng 7 2023

`(5x-1)^3`

`=(5x)^3 -3*(5x)^2 *1+3*5x*1^2 -1^3`

`=125x^3 -75x^2 +15x-1`

11 tháng 7 2023

(5x1)3

=(5�)3−3∗(5�)2∗1+3∗5�∗12−13=(5x)33(5x)21+35x1213

=125�3−75�2+15�−1=125x375x2+15x1