Cho hàm số y=-x3+25 có y'=0 thì x nhận giá trị 
A. x=±53.
B. x=±35.
C. x=0.
D. Cả A, B, C đều sai.

Hàm số có y’ = -xsinx là
A. y = xcosx.
B. y = xcosx - sinx.
C. .
D. y = xcosx + sinx.

Choose the best answer for the following sentence:
A ______________ is a story long enough to fill a complete book, in which the characters and events are usually imaginary. 
A. pleasure                   
B. novel                     
C. page                    
D. review

Choose the best answer for the following sentence:
_______________ symbol of the SEA Games Federation is to emphasize the solidarity, friendship, and nobility. 
A.  A                 
B. An                   
C. The               
D. Ø

Tìm giới hạn  
A.  
B.  
C.  
D. 0

Choose the best answer for the following sentence:
The serious critic, with the ______________ of humor and the power of expression, must inevitably command the world's ear. 
A. sense         
B. meaning               
C. ability               
D. feeling

Choose the best answer for the following sentence:
They have plenty of time, so they needn’t ___________. 
A. be hurry            
B. to hurry             
C. hurry                 
D. to be hurried

Choose the best answer for the following sentence:
I think you should have your house _______________ for the new year.
A. be decorated 
B. been decorated
C. to be decorated 
D. decorated

Với f(x)=1-x2 thì f'(2) là
A. Không tồn tại.
B. 23.
C. -23.
D. 2-3.

Choose the best answer for the following sentence:
The ________________________ toys are cheap. 
A. cliilds'               
B. children's                 
C. childrens'                     
D. childrens