a) ( x − 2 ) ( x 2 + 2 x + 4 ) = ( x − 2 ) ( x 2 + 2 ⋅ x + 2 2 ) = x 3 − 2 3 = x 3 − 8 b) ( x + y + 3 ) ( x − y − 3 ) = x 2 − x y − 3 x + x y − y 2 − 3 y + 3 x − 3 y − 9 = x 2 − y 2 − 6 y − 9 c) ( x + 1 ) ( x 2 + 1 ) ( x 4 + 1 ) = ( x 3 + x + x 2 + 1 ) ( x 4 + 1 ) = x 7 + x 3 + x 5 + x + x 6 + x 2 + x 4 + 1 = x 7 + x 6 + x 5 + x 4 + x 3 + x 2 + x + 1 d) ( 2 x 3 − 9 x 2 + 11 x − 3 ) : ( 2 x − 3 ) = ( 2 x 3 − 6 x 2 + 2 x − 3 x 2 + 9 x − 3 ) : ( 2 x − 3 ) = [ 2 x ( x 2 − 3 x + 1 ) − 3 ( x 2 + 3 x − 1 ) ] : ( 2 x − 3 ) = ( 2 x − 3 ) ( x 2 − 3 x + 1 ) : ( 2 x − 3 ) = x 2 − 3 x + 1 e) ( x y − x ) ( x 2 y 2 + 2 x 2 y + x 2 ) = ( x y − x ) [ ( x y ) 2 − 2 x y ⋅ x + x 2 ] = ( x y ) 3 − x 3 = x 3 y 3 − x 3

Viết lại câu sau đây ở dạng câu điều kiện loại 1.

1. He can’t go out because he has to study for his exam.
=> If ____________________________________________________________
2. She is lazy so she can’t pass the exam.
=> If ____________________________________________________________
3. He will pay me tonight; I will have enough money to buy a ca.
=> If ____________________________________________________________
4. He smokes too much; that’s why he can’t get rid of his cough.
=> If ____________________________________________________________
5. She is very shy, so she doesn’t enjoy the party.
=> If ____________________________________________________________
6. I will get work permit. I will stay for another month.
=> If ____________________________________________________________
7. He doesn’t take any exercises. He is so unhealthy.
=> If ____________________________________________________________
8. We can’t get the ticket because I don’t have money.
=> If ____________________________________________________________
9. Study hard or you won’t pass the exam.
=> If ____________________________________________________________
10. Don’t be impatient or you will make mistakes.
=> If ____________________________________________________________

$\frac{x^3+x^2-12}{x-2}=\frac{x^3-2x^2+3x^2-12}{x-2}$

$=\frac{x^2\left(x-2\right)}{x-2}+\frac{3\left(x-2\right)\left(x+2\right)}{x-2}$

=x^2+3x+6

=>Chọn C

7B 8A

Ta có : 3 , 09 × 10 9 = 3 , 09 × 10 × 10 8 = 30 , 9 × 10 8 Mà 30 , 9 > 8 , 27 Vậy 8 , 27 × 10 8 < 3 , 09 × 10 9

9/25; 5/6; 0,36 = 36/100 = 9/25