Cho biết ${\displaystyle \underset{0}{\overset{1}{\int }}x\sqrt{x^2+1}\text{d}x}=\frac{a\sqrt{2}-1}{b}$ với $a,b$ là các số tự nhiên. Giá trị của $a^2-b^2$ bằng

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Một số câu hỏi khác có thể bạn quan tâm.

• Choose one sentence that has the same meaning as the root one:

  Can you show me the camera over there, please?
  
  

• Choose one sentence that has the same meaning as the root one:

  The man was shot in the bank robbery. The doctors are operating on him.
  
  

• Choose one sentence that has the same meaning as the root one:

  I am interested in the books. The books were written by Jack London.
  
  

• Choose the word that has the underlined part pronounced differently from the rest:

   excuse                  socialc                  carry               culture

• Choose the best answer for the following sentence:

   We have to buy more food in _______________ for some unexpected guests.

   

• Choose the best answer for the following sentence:

   He’s always been very ________________ to me.

   

• Choose the best answer for the following sentence:

   Attending parties is one of the good chances to _______________ with other people.

   

• Find a mistake in the four underlined parts of the sentence and correct it:

  The beach on where we used to lie for sunbathing is very nice and clean.

• Choose the best answer for the following sentence:

  Peter suggested __________ out for a drink but everybody refused and kep

  on _________ .

    

• Find a mistake in the four underlined parts of the sentence and correct it:

  The storm N°9, for which we are waiting, have changed its direction.