\(A=(xy^2-1)(x^2y+5)-xy^2(x^2y+5)\\=(x^2y+5)(xy^2-1-xy^2)\\=(x^2y+5)\cdot(-1)\\=-x^2y-5\)

A=( xy^2-1)(x^2y+5)-xy^2( x^2y+5)

=xy^2.(x^2y+5)-1.(x^2y+5)-x^3y^3-5xy^2

=-x^2-5 ( bước này làm tắc )

1 if you don't study for the test, you won't get a passing score

2 Unless you follow the map, you won't reach your destination

3 I am keen on reading books about ancient cultures

4 John wanted to finish the marathon; however, he couldn't overcome the pain in his leg

5 Meeting the tribal groups was interesting

Question 1. Sa Pa / known / its / beautiful / mountains / valleys.

Sapa is known for its beautiful mountains and valleys

Question 2. British children / hang / small bells / gifts / Christmas trees.

British children hang small bells and gifts on Christmas trees

Question 3. If / you / not / take off / shoes, you / make / carpet / dirty.

If you don't take off your shoes, you will make the carpet dirty

Question 4. Our school / have / tradition / hold / talent show / every spring.

Our school have the tradition of holding a talent show every spring

Question 5. Vietnamese students / visit / Temple of Literature / pray / good luck.

Vietnamese students visit the Temple of Literature to pray for good luck

Question 1:Sapa is known for its beautiful mountains and valleys                                                                                                              Question 2:British children hang small bells and gifts on Christmas trees                                                                                                    Question 3:If you don't take off your shoes, you will make the carpet dirty                                                                                                    Questioon 4:Our school have the tradition of holding a talent show every spring                                                                                         Question 5:Vietnamese students visit the Temple of Literature to pray for good luck

a, Vì IK // EF

  ⇒ \(\dfrac{DI}{DE}\) = \(\dfrac{IK}{EF}\) (theo định lí talet)

  ⇒ \(\dfrac{DI}{DI+IE}\) = \(\dfrac{IK}{EF}\)

⇒ \(\dfrac{9,5}{9,5+28}\) = \(\dfrac{8}{x}\)

⇒ \(\dfrac{9,5}{37,5}\) = \(\dfrac{8}{x}\)

⇒ \(x\) = 8 : \(\dfrac{9,5}{37,5}\)

    \(x\) = 31,57 

Vì AB \(\perp\) BC;

   CD \(\perp\) BC

⇒ AB // CD (hai đường thẳng cùng vuông góc với một đường thẳng thứ ba thì song song với nhau)

⇒ \(\dfrac{AB}{CD}\) = \(\dfrac{BO}{OC}\)

   \(\dfrac{4,2}{x}\)  = \(\dfrac{3}{6}\)

   \(\dfrac{4,2}{x}\) =  \(\dfrac{1}{2}\)

     \(x\)    = 4,2 x 2 : 1 

      \(x\)   = 8,4