Mặc dù biết hơi kì nhưng chúc mọi người ở hoc24 sẽ thi THẬT THẬT TỐT nhé!

Mong các bạn sẽ có điểm 8,9,10 để cười sau thi và còn đi quẩy tết nha !

hi vọng các bạn sẽ có cái đầu ko trôi kiến thức, bạn phòng thi tốt bụng, giám thị thi "hiền hậu" như"mẹ hiền"....

x+3=x-1+4

x-1 chia hết cho x-1.

=>4 chia hết cho x-1.

Lập bảng các ước của 4 ra rồi tìm x.

b)2x+1=2x-12+13.

=2.(x-6)+13

x-6 chia hết cho x-6=>2.(x-6) cũng vậy.

=>13 chia hết cho x-6.

Tương tự.

Vòng phản xạ: luồng xung thần kinh và và đường phản hồi tạo nên vòng phản xạ.

Xe tăng và xe hơi cùng qua chỗ sình lầy, nhưng tại sao xe hơi lại di chuyển có khăn hơn xe tăng, mặc dù xe tăng có khối lượng nặng hơn xe hơi nhiều lần ? Em hãy giải thích dựa trên kiến thức Vật lý của mk ?

1)    tc :     x² + 2x +3  =   x² + 2x + 1 + 2   =   (x+1)² +2 > 0 vs mọi x

     => căn thức có nghĩa vs mọi x

2)    tương tự câu 1:   x² - 2x + 2  =  (x-1)² +1   >    0   vs mọi x

        => căn thức có nghĩa vs mọi x

3)    \(\sqrt{x^2+2x-3}\)có nghĩa    <=>  x²+2x-3\(\ge0\)

                                                          <=> (x+1)² - 4 \(\ge0\)

                                                        <=> (x+1)² \(\ge4\)

                                                         <=> x+1 \(\ge2\)

                                                         <=> x \(\ge1\)

4) \(\sqrt{2x^2+5x+3}\)có nghĩa   <=>  2x² +5x +3 \(\ge0\)

                                                      <=> 2x² + 2x + 3x + 3 \(\ge0\)

                                                      <=> (2x+3)(x+1) \(\ge0\)

                                                       <=>\(\hept{\begin{cases}2x+3\ge0\\x+1\ge0\end{cases}}\)  hoặc    \(\hept{\begin{cases}2x+3\le0\\x+1\le0\end{cases}}\)

                                                     <=>  \(\hept{\begin{cases}x\ge\frac{-3}{2}\\x\ge-1\end{cases}}\)        hoặc   \(\hept{\begin{cases}x\le\frac{-3}{2}\\x\le-1\end{cases}}\)

                                                    <=>   \(\frac{-3}{2}\le x\le-1\)

Bạn tham khảo nha ;

Nowadays most people in the world have had a contact with computers. A majority of them has been using international computer's network known as the Internet -the mass media you often work

On my view, using internet has more advantages than disadvantages. Firstly, the Internet provides access to a lot of information. Some of them are very useful in your job other helps in your hobby. Searching with Google, you can find everything you want. You can do shopping through the Internet. Of course, it has no sense to buying a roll, but if you need something inaccessible, you will be able to buy it in Internet shop. You just need only to select what you want, fill in some forms and click ok. In a few days, you will get what you have ordered to your home directly, without going anywhere.

You also can pay with your credit card, pay postman when you get the package, or transfer money from your bank account. Today, almost bigger bank offer transferring money through the Internet. It is faster than going to the bank and filling the forms. Transferring money in traditional way takes about a day, but using Internet you can do this in few seconds even on Saturday and Sunday.

What’s more internet banks give you insurance against unauthorized transaction. Some people think that their money can be stolen by hackers easily. It isn’t true because the easiest way to steal your money from internet bank is breaking to your house and stealing your bank codes. Internet banks have very good protections witch make them practically unbreakable.

Next advantage of internet is email. Internet emails get in a few seconds in their destinations. It is very important when you want to send something to somewhere far from your place, for example Australia. Of course you can send whatever you want, not only texts such as movies, photos, songs, computer programs and so on. And sending an email is much cheaper than phoning, or sending normal letters.

Beside a lot of advantages, Internet also has some disadvantages too. First of disadvantages is that people who spend too much time sitting in the front of computer can easily get ill. Radiation emitted by computer’s screen is harmful to eyes. People who spend too much time at their homes (because they do not need to go anywhere, they can do everything by using Internet) are getting weaker. Sitting for a long time is also harmful to the spine. The second disadvantage is that Internet can by addictive. Some people just can’t live without it. They have no real friends and when Internet is down they are getting furious.

Internet has some opponents but more and more people treats Internet like telephone, or radio. They use it for fun and work. In my opinion, at present living without internet would be quite difficult.

Ta có: 12+[ 8 * x ]=28 

=> 8 * x = 28 - 12

=> 8 * x = 16

=> x = 16 : 8

=> x = 2

Chu vi hình vuông :

3 x 4 = 12 ( m )

Nửa chu vi hình chữ nhật:

12 : 2 = 6 ( m )

Vì nửa chu vi = chiều dài + chiều rộng

nên tổng của chiều dài và chiều rộng là 6m.

=> Đáp số: 6m